Liqiang Cao

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Beijing University of Technology | Bei Gong Da · College of Architecture and Civil Engineering

This paper develops a semi-analytical method to calculate the ground movements due to tunnelling in multi-layered clayey soils which are usually encountered in urban areas. The proposed method is based on the modified Loganathan-Poulos formula combined with the elastic equivalent theory. The key issue disposed in current study is the transformation...

This paper presents a theoretical method for the horizontal mechanical responses of single pile due to tunnelling in multi-layered soils. Based on the homogenization theory and the integral L&P formula, ground horizontal displacements due to tunnelling in layered soils can be solved analytically. The pile-soil interaction model is established in wh...

This paper presents a simplified elastic continuum method for calculating the restraint effect of isolation piles on tunneling-induced vertical ground displacement, which can consider not only the relative sliding of the pile‒soil interface but also the pile row-soil interaction. The proposed method is verified by comparisons with existing theoreti...

The reasonable setting of the slurry pressure is very important for the safety of shield tunnel construction. In view of the common geological problems of high water pressure and multiple fracture zones in water conveyance tunnels in China, the instability mechanism of the shield excavation face in these formations remains unclear. In this paper, b...

The mechanical evaluation of multiple shallow tunnels is essential for predicting the potential risk. In previous analytical studies, the Schwarz alternating method is the unique tool to calculate the mechanical field of multiple shallow tunnels through a complicated iterative process. This work will develop a novel analytical method to calculate t...

An accurate second-order spatial and temporal finite-difference scheme is applied to solve the dynamics model of a depth-averaged avalanche. Within the framework of the MacCormack scheme, a total variation diminishing term supplements the corrector step to suppress large oscillations in domains with steep gradients. The greatest strength of the sch...

This paper presents an analytical method to predict the response of a strip foundation building to shallow tunneling based on the two-stage method. The existing building is simplified as a Euler–Bernoulli beam resting on the Pasternak model. The tunneling process and different relative positions between the tunnel and the existing building can be c...

This paper proposes an elastic solution for evaluating tunneling-induced vertical ground displacements due to the restraint of embedded isolation piles. Based on the modified Loganathan-Poulos (L&P) formula and the general form of the Melan/Mindlin solution, the restrained tunneling-induced vertical ground displacements can be calculated according...

Shield tail sealing is a critical problem that influences work safety during shield tunneling processes. In recent years, the number of accidents caused by the failure of shield grease during shield tunnel construction has gradually increased. Taking Foshan Metro Line 2 accident as the research background, this study adopts the indoor model test an...

Shield tunnels are often exposed to high water pressures, owing to which, the dynamic sealing of shield tail grease under high water pressure has been rarely studied in the past. In this research, a dynamic sealing test device for the shield tail grease under a high water pressure was developed. Through this test equipment, three representative gre...

Tunnelling-induced environmental responses including ground movements and deformation of the environmental structures are the two prominent issues needed to be carefully disposed in urban areas. This paper tries to develop a theoretical framework to evaluate and control the environmental deformation to avoid two disasters including ground collapse...

This paper proposes a simple yet efficient mortar-type method to couple independent finite element subdomains with intersecting interfaces. In this method, we split the subdomain interfaces into several contact patches. Different patches are allowed to have the same master/slave nodes. To eliminate the over-constrained behavior that often occurs in...

Based on the nondestructive test data of operating railway tunnels in China, this paper summarizes the basic characteristics of the complex contact behavior between the rock mass and lining structure. The contact modes are classified into dense contact, local non-contact, and loose contact. Subsequently, the corresponding mechanical model for each...

It is of great scientific and practical significance to carry out the mechanical response assessment and process control of the environment due to tunneling in urban areas. Firstly, based on the prediction method for ground deformation of the single layer ground, the deformation prediction theory of complex combined layered ground is established th...

A case of Qinghuayuan tunnel excavation below the existing Beijing Subway Line 10 is presented. The new Qinghuayuan tunnel, part of the Beijing-Zhangjiakou High-speed Railway, was excavated by a shield machine with an outer diameter of 12.2 m. The existing subway was excavated by shallow tunnelling method. The project layout, geological conditions,...

The platform of the Badaling Great Wall Underground Station consisted of large span triple tunnels. The triple tunnels passed through several major faults. Based on preliminary in situ monitoring, the interaction behavior among triple tunnels was significantly severe, and the original supports failed to meet the safety requirement. Therefore, pipe...

To study the mechanical responses of large cross-section tunnel reinforced by pretensioned rock bolts and anchor cables, an analytical model is proposed. Considering the interaction between rock mass and bolt-cable support, the strain softening characteristic of rock mass, the elastic-plastic characteristic of bolt-cable support, and the delay effe...

Microseismic monitoring technique has great advantages on identifying the location,extent and mechanism of damage process occurring in rock mass.In-situ test using microseismic monitoring technique is carried out in the large-span transition tunnel of Badaling Great Wall Station of Beijing-Zhangjiakou high-speed railway.An intelligent microseismic...

Based on the Tsinghuayuan Tunnel Project of Beijing-Zhangjiakou High-speed Railway,this paper focuses on the barrier characteristics of vertical isolation measures against formation deformation propagation during shield tunneling.The displacement of three vertical isolation structures including bored piles,composite anchor piles and portal piers an...

In order to predict the law of surface subsidence caused by shield construction,time-series based NARNN(without external input)and NARXNN(including external input)models of non-linear input autoregressive neural network prediction are established based on the large-diameter mud-water shield tunnel project of Qinghua tunnel project of the newly buil...

Three-bench seven-step excavation method (TSEM) has been widely used in large-section loess tunnels for high-speed railway in China. As the most commonly applied pre-supports, pipe roofs and leading ductules are broadly used in the ground reinforcement of loess tunnels. Their application is to ensure face stability and prevent tunnel collapse durin...

The drill and blast method is widely used in constructing tunnels in rock. Unfortunately, blasting vibration can damage newly performed shotcrete layers which are major support structures to stabilize surrounding structures. Therefore, investigation of the influence of blasting on shotcrete and determining reasonable distance between blasting work...

This paper illustrates the surface settlement characteristics of subway station construction in the shallow-buried soft ground using the pile-beam-arch (PBA) approach of the shallow tunnelling method. The geological conditions, cross sections and measured surface settlements of 30 subway stations constructed by the PBA approach in Beijing are prese...

Based on the semi-contained water model,comprehensively considering the permeability of the shieldcrossing soil layer and the overburden layer when shield passed through the permeable soil, the analytical solution of the head distribution along the tunnelling direction within the shield-crossing soil layer was derived, combining this,the analytical...

In this study,the common wedge model was revised and a quadrangular wedge model was built based on model test of the shield tunnel working face in clay layer and the failure mode obtained from the numerical simulation.With the limit equilibrium method,the analytical expression of the limit support pressure at shield tunnel working face in clay laye...

The distribution characteristics of pore water pressure under steady seepage condition of groundw ater was calculated based on numerical simulation as shield advanced in saturated sand,then the function of vertical pore water pressure in the overburden and horizontal w aterhead in the tunnel-passing layer were obtained using the above calculated da...

A method for calculating ground vertical displacements of double-layor elastic system due to shield tunneling was proposed combining the stiffness equivalent method with the Mindlin solution，which can simultaneously consider the unbalanced force at the tunnel face，the friction between the shield skin and the soil, the grouting pressure of the shiel...

Based on the analysis of the key construction elements of earth pressure balance (EPB) shield tunnel, a refined numerical simulation method for analysing seepage-stress coupling is proposed. Relying on the shield tunnel project of the section from Tiantuo Station to First Central Hospital Station of Tianjin Subway Line 6, the influence of key const...

During slurry shield tunneling, a filter cake with low permeability will be formed on the working face when pressurized slurry infiltrates into the stratum. To ensure the stability of the working face, the slurry pressure which acts on the filter cake that is almost impervious to water to counteract the soil pressure and water pressure. Based on th...