Enlong Liu

• Ph.D
• Professor (Full) at Sichuan University

Particle shape and local breakage significantly affect the deformation characteristics of crushable granular materials. However, in the existing constitutive model research, there is less introduction of particle shape on particle breakage. A quantitative parameter for the three-dimensional particle shape (Average spherical modulus \(\overline{G_{M...

This study aimed to thoroughly investigate the shear resistance and movement dynamics of dry granular flow by utilizing a discrete element method (DEM) approach. Its focus was on exploring the effects of varying interparticle friction coefficients and slope angles on these processes. A DEM model was developed, integrating critical input parameters...

In cold regions, the frozen soil–rock mixture (FSRM) is subjected to cyclic loading coupled with freeze–thaw cycles due to seismic loading and ambient temperature changes. In this study, in order to investigate the dynamic mechanical response of FSRM, a series of cyclic cryo-triaxial tests were performed at a temperature of −10 °C on FRSM with diff...

Natural freeze–thaw (FT) cycles and earthquakes are two key triggers for landslides in cold regions. However, investigations on their coupled effect are rare. In the current work, this coupled effect was investigated by shaking table tests of two slopes, namely a non-freeze–thaw (NFT) slope and a FT slope. Results indicate that the slope’s natural...

This study investigates the effects of interface shape and bonding conditions on the side friction resistance of the cast-in-place pile in coral reef limestone stratum of the China-Maldives Friendship Bridge area. Large-scale direct shear tests are performed on the coral reef limestone-concrete interface to investigate the exertion mechanism of int...

To investigate the unloading mechanical properties of deeply buried silty soil in dam foundation cover layers, a series of consolidated drained triaxial compression tests along multi-stage loading–unloading path were performed on both undisturbed samples (including horizontally and vertically oriented samples) and remolded samples. The test results...

The artificial cemented granular particles were prepared to simulate the rockfills, and conventional triaxial drainage tests were conducted to explore the mechanical properties of granular materials under different confining pressures. Furthermore, the results were simulated based on the discrete element method. Test results from the laboratory tes...

In order to study the mechanical properties of the upper loosely-paved gravelly soil used to protect the compacted dam material under the freeze–thaw cycle during winter construction on the engineering site, the gravelly soil with the soil-rock ratio of 7:3 was mixed evenly and sealed under the corresponding dry density and moisture content, and th...

Geothermal heating and cooling is a new type of building energy-saving technology that utilizes surface geothermal energy, which causes temperature changes in the surrounding geotechnical bodies when it works, and affects the strength characteristics of loess when it is applied in loess areas. To investigate the change in the strength of intact loe...

In order to master the strength and deformation characteristics, including the macro–micro failure mechanism of soft rock samples with penetrating joints under triaxial loading, a series of numerical triaxial tests have been carried out. The strength and deformation characteristics, failure modes, crack propagation, distribution of force chains, an...

Triaxial tests are performed for remolded, artificially isotropic, and anisotropic structured samples under undrained conditions at confining pressures of 25, 100, and 200 kPa. Based on these test results, a binary-medium constitutive model is formulated based on homogenization theory and a breakage mechanism to describe the behaviors of structured...

Revealing the damage mechanism of jointed rocks under a cyclic loading and formulating the corresponding dynamic constitutive model to meet the requirements for the evaluation of anti-vibration safety for critical engineering construction and operation is an essential, urgent and basic subject. Based on the breakage mechanics for geological materia...

The drill and blast (D&B) method is widely used to excavate underground spaces, but explosions generally cause damage to the rock. Still, no blast simulation method can provide computational accuracy and efficiency. In this paper, a blast equivalent simulation method called the blast damage zone strength reduction (BDZSR) method is proposed. This m...

Rock avalanches are generally difficult to prevent and control due to their high velocities and the extensive destruction they cause. However, barrier structures constructed along the path of a rock avalanche can partially mitigate the magnitudes and consequences of such catastrophic events. We selected a rock avalanche in Nayong County, Guizhou Pr...

This research investigates the permeability and compressibility performance of aeolian-Na/Ca-bentonite mixtures (ANB/ACB) with varying bentonite contents, subjected to different freeze–thaw cycles, in which the particle size analysis, permeability tests, and compression tests are employed. The results indicate that: (1) with increasing bentonite co...

Reef limestone is the foundation of marine geotechnical engineering. It is very important to understand the mechanism of interface failure between reef limestone, a special porous medium of geotechnical engineering material, and concrete in actual projects, and in this study, the Finite-Discrete Element Method (FDEM) is employed to investigate this...

This is a live video taken on May 11, 2023 of the Songpan landslide.

Diurnal freeze–thaw process occurs in the Lianghekou area in winter, which will affect the construction progress and quality of the project. In this paper, the compressibility of clay experiencing the freeze–thaw (F-T) cycles under different impacting factors was investigated. A series of unidirectional F-T tests were carried out in a closed system...

Creep deformation control is the key point and difficulty in the construction of loess high fill, the creep characteristics of loess with different compactness and confining pressure conditions has been studied. To achieve the objective, the influence of different conditions on the creep deformation characteristics of loess were analyzed by the tri...

Different from other geotechnical materials, the strength characteristics of saturated frozen soil have nonlinear characteristics that first increase and then reduce with the increasing confining pressure, and are sensitive to varying temperature due to the existence of ice inclusions. Based on analysis on the breakage of frozen soil, it is believe...

A slope on the right side of China’s Sichuan-Qinghai traffic corridor in Songpan County, Sichuan Province, experienced successive landsliding on May 10th, 2023. The event caused significant damage, including blocking the G213 National Highway and the Minjiang River and disrupting power supply lines. The event posed a threat to the safety of downstr...

To investigate the mechanical properties and constitutive models of structured soil under undrained conditions, triaxial compression tests on initially anisotropic structured soil, isotropic structured soil, and remolded soil were conducted under consolidation undrained conditions at confining pressures of 25, 50, 100, and 200 kPa, respectively. Th...

The surrounding rock and slope of the exit of the No. 1 drainage tunnel of the Artashi Water Conservancy Project exhibited unpredicted deformation during excavation. The rock was determined to be micritic bioclastic limestone containing 55% bioclastic material, which has not been sufficiently studied. Conventional triaxial compression experiments o...

In this paper, the triaxial compression tests with different confining pressures and strain rates are carried out on polycrystalline ice samples at − 6 °C, and under these conditions all the samples behave strain softening, with volumetric contraction followed by dilatancy at the lower confining pressure, and dilatancy at the higher confining press...

The single cleavage drilled compression specimens of sandstone were impacted by the large-diameter split Hopkinson pressure bar, the whole model-I dynamical fracture process was successfully observed. A crack propagation gauge is used to monitor the key time moment of dynamic initiation, propagation, arrest and re-initiation, respectively. The frac...

In seasonally frozen soil, soil sometimes is affected by freeze–thaw cycles and root systems. In order to study its mechanical characteristics, a series of consolidation drained triaxial tests under different confining pressures (25, 50, 100, 200 kPa), different freeze–thaw cycles (N = 0, 1, 5, 15) and different root-containing conditions (r = 0, 1...

Since all the soil materials within 200 kilometers of the proposed dam site are aeolian sedimentary soil, the permeability is not in line with the engineering performance of the core dam materials. Moreover, in the construction of a large core dam in a high altitude area, the core wall dam materials will be subjected to repeated freeze-thaw action...

A micro-macro elastoplastic micropolar continuum model for granular materials in the dry and pendular states is proposed on the basis of thermodynamics. The independent rotational degrees of freedom are considered besides the translational degrees of freedom for particles among the discrete particle system, which is described by the equivalent micr...

Mountainous areas in southwest China are rainy in summer. The rainfall infiltration process involves complex soil thermal-hydraulic-mechanical (THM) coupling problems. The researches on soil THM coupling are mostly focused on numerical simulations, whereas the corresponding model tests are relatively few, and the existing model test studies often i...

The molecular dynamics method is used to further reveal, from the molecular point of view, the mechanisms of salt inhibiting the hydration of Na-MMT. The interaction between water molecules, salt molecules, and montmorillonite are calculated by establishing the adsorption models. According to the simulation results, the adsorption conformation, int...

Saturation conditions play a significant role in the mechanical behavior of granular material and the evolution of an interparticle contact system during the loading process. Using data derived from discrete element simulations of granular assemblies subject to triaxial compression loading with different suctions, we examine the properties of an in...

As new ways to solve partial differential equations (PDEs), physics-informed neural network (PINN) algorithms have received widespread attention and have been applied in many fields of study. However, the standard PINN framework lacks sufficient seepage head data, and the method is difficult to apply effectively in seepage analysis with complex bou...

In seasonally frozen soil, soil sometimes is affected by freeze-thaw cycles and root systems. In order to study its mechanical characteristics, a series of consolidation drained triaxial tests under different confining pressures (25,50,100,200 kPa), different freeze-thaw cycles (N = 0,1,5,15) and different root-containing conditions (r = 0,1,3) wer...

The slope stability of Ya’an expressway in Sichuan dominated by mudstone strata, is influenced greatly by both the mechanical properties and stressstrain relationship of mudstone. In this paper, the mechanical properties of the Ya’an mudstone samples under triaxial compression conditions were studied, based on an established constitutive model unde...

Taking the Jiangluling Carbonaceous Shale Tunnel as an example, this study aims to investigate the mechanism of large deformation and design construction technology of carbonaceous shale tunnels. Using theoretical analysis and comparative analysis of numerical simulation and field measured data, the mechanism, mechanical properties, and causes of l...

In this work, a binary-medium-based constitutive model for porous rocks is proposed under the framework of micromechanics. The porous rock at mesolevel is considered a two-phase composite composed of the matrix of the bonded medium and inclusions of the frictional medium. The bonded medium is defined by a Drucker-Prager solid phase where the pores...

This study aims to assess the influence of both discontinuities and seismic ground motions on the failure process of an artificially excavated slope in Ya’an, Sichuan, China. The geological background of this area is presented first, based on which a novel continuous-discontinuous method, combining the finite element method and discrete element met...

In cold regions, the deformation characteristics of frozen soils with different coarse-grained contents change significantly under the freeze-thaw (F-T) cycles. A series of cryogenic triaxial compression tests were conducted to investigate the deformation characteristics of frozen soil at-10°C experiencing freeze-thaw cycles. The results indicated...

In cold regions, the deformation characteristics of frozen soils with different coarse-grained contents change significantly under the freeze–thaw (F-T) cycles. A series of cryogenic triaxial compression tests were conducted to investigate the deformation characteristics of frozen soil at −10 °C experiencing freeze–thaw cycles. The results indicate...

Time-dependent deformation and long-term stability of rocks are important issues in water conservancy and geotechnical engineering. Currently, there are no well-accepted theoretical criteria with which to predict stability and damage considering time-dependent deformation. In-depth research is still needed. Multilevel creep experiments were perform...

As a widely-applied engineering material in cold regions, the frozen subgrade soils are usually subjected to seismic loading, which are also dramatically influenced by the freeze-thaw (F-T) cycles due to the varying temperature. A series of dynamic cyclic triaxial experiments were conducted through a cryogenic triaxial apparatus for exploring the i...

A rate-dependent constitutive model for saturated frozen soil is vital in frozen soil mechanics, especially when simultaneously describing the nonlinearity, dilatancy and strain-softening characteristics. The distribution of the non-uniform strain rate of saturated frozen soil at the meso-scale due to the local ice-cementation breakage is described...

The paper proposes a three-scale binary medium-based constitutive model on the basis of the meso structures and micro components to describe the elasto-plastic mechanical behavior of mudstone samples. Based on the breakage mechanism of geomaterials, mudstone samples are considered as two different materials (bonded and frictional elements) at mesos...

As a desirable bonding and repair material, epoxy resin combined with other materials is widely used in civil engineering, but its application in underground rock engineering is still limited compared with the wide use of cement grout. To explore and optimize the effect of room temperature-cured bisphenol A epoxy resin E44 on the strength recovery...

In order to study the dynamic behaviors of polycrystalline ice samples, cyclic triaxial loading tests were carried out on laboratory-grown polycrystalline ice (granular ice) samples under different temperatures (−2 °C, −6 °C, −15 °C), different confining pressures (0.5 MPa ~ 6 MPa), different frequencies, and different dynamic stress amplitudes. La...

Current knowledge on unsaturated soils suggests that the effective stress should be related to soil microstructures, by which the immobile water attached to the soil solid in micropores and the free water mainly governed by capillary effects in relatively large pores can be distinguished. Paying attention to this knowledge, the micro‐ and macroscop...

The mechanical properties of grout and the effect of the bonding between grout and the repaired material are the two main factors affecting the shear strength of the material. To study the effect of repairs carried out with nano-Al2O3/epoxy resin composite (NAEC) on the shear strength of rock masses, cracks with different widths and treatments by s...

The surrounding rock at the exit of the No. 1 drainage tunnel of the Artashi Water Conservancy Project is micritic bioclastic limestone with 55% bioclastic material. This rock underwent unpredictable large and time-dependent deformation during excavation. To date, the mechanical behaviour of this kind of rock has rarely been studied. In this study,...

This paper is devoted to determining the inelastic responses of geological materials by the binary-medium-based constitutive model. The geomaterials are conceptualized as two-phase composites that are composed of the bonded medium of elastic–brittle nature and the frictional medium of elastoplastic nature. The evolution of meso-structure upon loadi...

The mechanical and deformation mechanism of coral-reef limestone is vital for the stability and safety of infrastructures built on the ground composed of those materials. Upon loading, strain softening behavior of the coral-reef limestone occurs, usually due to the nonuniform cementation distribution, and the cementation within the samples may brea...

In order to analyze the meso-structure of debris flow, the debris flow model with different inter-particle friction coefficients and slope angles is established here by the CFD–DEM coupled approach. The simulated results demonstrate that the drag forces caused by the inflow velocity of the fluid will drive the shallow particles to be unstable initi...

A new type of steel–concrete–steel composite structure was adopted and widely used in the immersed tunnel of the Shenzhen–Zhongshan access. The research on the mechanical behavior of the new composite structure under a high temperature of fire is of great engineering significance to the fire protection design of the structure. Both the model test a...

Based on the similarity between the drying-wetting process and freezing-thawing process in the soil, a physically based equation predicting the soil freezing characteristic curve (SFCC) can be formulated combining the generalized Clapeyron equation. In this paper, by introducing the weighing factors in two scales of pore sizes, the physically based...

In permafrost regions, under the interference of climate warming and human activities, the deformation stability of geological engineering with frozen soil as the medium is directly affected, and the typical ones are the creep characteristics under the influence of temperature and stress level. In order to reveal the internal mechanism of such char...

Soil mass failure disasters are among the most destructive disasters in mountainous areas worldwide, and they continue to receive significant attention in the literature. However, factors that influence soil mass failure in hollows have not been explored via experimental approaches. In this study, we conducted a series of indoor hollow-flume experi...

In permafrost regions, under the interference of climate warming and human activities, the deformation stability of geological engineering with frozen soil as the medium is directly affected, and the typical ones are the creep characteristics under the influence of temperature and stress level. In order to reveal the internal mechanism of such char...

Purpose-The purpose of this paper is to perform the thermo-hydro-mechanical (THM) numerical analysis in order to study the thawing process for frozen soil and to predict the thawing settlement. Design/methodology/approach-A new one-dimensional multi-field physical coupled model was proposed here to describe the thawing process of saturated frozen s...

This study presents a poromechanics-based constitutive model for warm frozen soil. In the model, the effect of pressure melting on unfrozen water content is taken into account. Through the method of poromechanics, the model can consider the interaction between soil particles, ice crystals and unfrozen water. Both the unfrozen water pressure and ice...

Freezing–thawing actions can affect the mechanical features of soil greatly, which is vital for the stability of soil slope in cold regions. Firstly, triaxial compression tests on sand samples under undrained conditions were performed to investigate the influences of freezing–thawing cycles, which shows that the freezing–thawing actions can weaken...

Acid rain is mainly composed of sulfuric acid and nitric acid aqueous solutions, which can deteriorate the mechanical properties of soil and thus threaten the safety of soil engineerings. In this paper, the influence of sulfuric acid rain on mechanical properties of loess soil samples was studied. The diluted sulfuric acid solution has respectively...

In 2000, a high-speed remote landslide occurred in Yigong, Tibet, China, which traveled 10 km within 10 min with a final deposit volume of 300 Mm³, forming a dammed lake and causing huge losses and environmental damage. This study aims to numerically simulate the entire dynamic process of the Yigong landslide under seismic loading, focusing on its...

This paper focuses on investigating how a particular but classical configuration of a finite homogeneous soil layer, once studied by Terzaghi and currently subjected to freezing temperatures, behaves and how different boundary conditions can intervene and affect the thermo-hydro-mechanical (THM) responses. Spatial homogeneity is a strong assumption...

In cold regions at high altitudes, freeze-thaw cycles due to diurnal temperature variation in the construction process in winter result in the core-wall soil materials of dams having varying mechanical properties. In this study, a series of consolidated undrained triaxial tests were performed on soil samples subjected to various numbers of freeze-t...