Jianming Zhang

• Chinese Academy of Sciences

In permafrost regions, the warm and ice-rich frozen soil (WIRFS) underlying the embankment has a low strength and large compressibility, which threatens the engineering stability. The addition of cement and its additives can improve the mechanical properties of the WIRFS. During the curing and the thawing compression, the micro-structure of the imp...

The foundation of constructions built in the permafrost areas undergo considerable creeping or thawing deformation because of the underlying ice-rich permafrost. Soil improvement may be of advantage in treating ice-rich permafrost at shallow depth. Sulphoaluminate cement was a potential material to improve frozen soil. Simultaneously, two other cem...

Containing a considerable amount of unfrozen water, frozen soil may produce excess pore-water pressure under external load, especially at temperatures near the thawing point. The variation of the pressure has a capability in influencing the deformation of frozen soils. In order to investigate the variation behavior of pore-water pressure in frozen...

In order to determine the long-term deformation behavior of in-situ ice-rich permafrost under natural conditions, three deformation setups utilizing a plate loading method were built in a permafrost region on the Qinghai–Tibetan Plateau. The loading plates were installed just below the permafrost table, and loads were applied via platforms that wer...

Warm and ice-rich frozen soil (WIRFS) exhibits lower shear strength due to the weak binding forces between soil particles and ice crystals. To enhance the strength of WIRFS, frozen soil was treated separately with Portland, Phosphate, Sulphoaluminate, Portland-Phosphate and Portland-Sulphoaluminate cements. After the samples were cured under -1.0°C...

Warm frozen soil has characteristics such as low shear strength and high compressibility. To improve its mechanical strength, the ionic polymer soil stabilizers (IPSS): named XRH stabilizer and acid cation exchange resin (CER) were adopted for reinforcing the warm frozen soil from the Beiluhe region of the Qinghai-Tibetan Plateau. To evaluate the e...

The warm and ice-rich frozen soil (WIRFS) that underlies roadway embankments in permafrost regions exhibit large compression and thaw deformation, which can trigger a series of distresses. Cement and additives were used in this study to improve the compressibility and thaw-settlement properties of WIRFS. We, therefore, selected optimum additives an...

In this paper, the dry cement was mixed with warm and ice-rich permafrost to improve its mechanical and physical properties. The changes of temperature of improved soil with different cement dosage were measured by in-situ test. Then, the temperature field of the improved soil in-situ test was calculated by mathematical model of heat conduction and...

In the context of climate warming, damage to road pavements and embankments in permafrost regions caused by thawing of underlying permafrost severely reduces the serviceability of roads. In this study, 10 types of asphalt pavement damage were measured every kilometer along the Qinghai–Tibet Highway (QTH), from Kunlun Mountain to Tonggula Mountain (...

Ionic soil stabilizers (ISS: acidic and alkaline) were adopted for the stabilization treatment of warm frozen soil from the Qinghai–Tibet Plateau. To evaluate the effects and analysis mechanisms of the ISS on warm frozen soil, laboratory tests were conducted to measure the mechanical, physical and chemical properties of frozen soil treated with ISS...

In this paper, a one-dimensional creep model that takes temperature as an independent variable was proposed for frozen soils. A series of K0 compression tests was conducted under different constant surcharge loads with stepped increases in temperature. An analysis of the test results indicated that the characteristics of creep strain, developing du...

Thermal regime evolution and settlement behavior of a riverbank over ice-rich permafrost in 20 years were estimated by numerical simulation and layerwise summation calculation. The results show that the permafrost under the riverbank will undergo a thawing process at a dramatically rate under the conditions of practical geology and construction str...

Timely and proper backfilling of open-pits in strip coal-mines has been an effective measurement for the recovery of the hydrothermal regimes and ecological environment in permafrost regions. In this study, numerical simulations and statistical regressions were applied for analyzing the recovery processes of the backfill and its major influencing f...

The effect of nine cement additives on the unconfined compressive strength (UCS) of warm and ice-rich frozen soils was analyzed. After 7 days of curing at −1 °C, the UCS at −1 °C, the freezing-point depression and changes in the water content of soil samples were measured to explore the additive effect and mechanism. The optimum additive dosage was...

In order to study the deformation behavior of in-situ warm and ice-rich permafrost with seasonally varying ground temperature, two groups of plate load tests were carried out in permafrost region on the Qinghai-Tibetan Plateau. The test results showed that the deformation of the permafrost under a constant load always represented a stepped pattern...

A riverbank was constructed on ice-rich permafrost in the far north of China in 2015, and its performance is closely related to the thermal stability of the permafrost foundation. To investigate the thermal regime evolution of the foundation, a numerical simulation using a coupled hydro-thermal model that involves concrete hydration, heat transfer...

In order to analyze the distribution characteristics of subgrade distresses of the Qinghai-Tibet Highway (QTH) in permafrost regions, explore the relationship between influencing factors and diseases, quantitatively calculate the weight of each factor on diseases and ultimately forecast the probability of susceptibility of subgrade diseases, this p...

A series of compression experiments was conducted to observe the pore-water pressure variations of saturated warm frozen soils over time. The results indicate that saturated warm frozen soils can exhibit excess pore-water pressure when subjected to external loads. The pore-water pressure fluctuates rather than varying monotonically, and it graduall...

On the basis of the Biot’s consolidation theory, a thermo-hydro-mechanical (THM) model was presented for computing the settlement of warm frozen soils under an external load. The proposed model allowed the unfrozen water in the soils to migrate according to the effective stress principle. In addition, the pressure potential due to loading was consi...

In order to cognize the permeable property of the frozen silty clay spreading widely in permafrost regions on the Qinghai-Tibet Plateau, a series of laboratory tests are conducted to measure the hydraulic conductivities of the frozen silty clays with moisture content of 50% at temperatures from -0.6 to 0.1℃. The results show that under the warm neg...

High-grade highways designed for large traffic volumes need wider embankments than railways and low-grade highways. In permafrost regions, a wide and dark-colored asphalt pavement surface of high-grade highways may destabilize underlying permafrost if the embankment is insufficiently cooled, especially under a warming climate. However, the embankme...

Stability of the embankment is largely concerned with the height and pavement type in permafrost area. Climate is another key factor. The heat transfer model with phase change and finite element method are used to simulate the thermal regime of permafrost beneath embankment of Qinghai-Tibet Highway, considering the changing of pavement type, height...

In order to identify the relationship between pressuremeter tests and indoor tests, the pressuremeter tests and uniaxial tests were performed and the comparisons between the test results were analyzed. The results indicate that the pressuremeter creep curve presents a decaying form; while a progressive flow stage appears in the uniaxial test once t...

In order to mitigate frost jacking of the foundations, most of the towers in permafrost regions along the Qinghai-Tibet Power Transmission Line from Golmud, Qinghai Province to Lhasa, Tibet Autonomous Region, China were installed on precast or cast-in-place footings. However, the monitoring data showed that these footings were suffering more from s...

Creep of frozen soils is one of the most important issues in cold regions engineering. This paper first reviews the state-of-the-art of creep models for frozen soils. It is found that the elementary rheological models are more feasible in describing the creep of frozen soils. The authors propose a simple model by combining Maxwell, Kelvin and Bingh...

The adfreezing bond strength between soils and foundation surface plays an important role in general stability concerns of foundations in frozen ground. A series of laboratory direct shear tests on the adfreezing interface between silt and concrete are performed to understand the mechanical behaviors of the foundation-frozen soil interface. The res...

In order to investigate the creep behavior of warm and ice-rich frozen soils, a number of pressuremeter tests were carried out in permafrost regions on the Qinghai-Tibetan Plateau with Menard pressuremeter. Then, the regression analysis results of the creep curves generated by Merchant model and relevant parameters were obtained. The test results i...

In order to investigate the creep behavior of high-temperature and high ice-rich frozen soils, a series of pressure tests were carried out in permafrost regions on the Qinghai-Tibetan Plateau. The test results showed that it was acceptable to describe the pressure creep curve employing the engineering theory of creep proposed by Ladanyi. The averag...

The Qinghai-Tibet ±400 kV electrical transmission line traverses more than 550 km in permafrost regions, which may lead to a lot of frozen soil engineering problems for the foundations of transmission tower. Since the column foundation can not only reduce frost heave force but also provide higher bearing capacity, it has been accepted as the first...

In order to investigate the in-situ mechanical behavior of warm and ice-rich frozen soils, a series of pressuremeter tests were carried out in permafrost regions on the Qinghai-Tibetan Plateau. Based on the test results, the relationship between stress and strain was obtained using Ladanyi's theory, and it can be described by a hyperbolic model. Mo...

Assessing possible permafrost degradation related to engineering projects, climate change and land use change is of critical importance for protecting the environment and in developing sustainable designs for vital infrastructure in cold regions. A major challenge in modelling the future degradation of permafrost is finding ways to constrain change...

The Qinghai-Tibetan ±400 kV direct current grid interconnection project runs across 1038 km of permafrost and seasonally frozen-ground in the interior of the Qinghai-Tibetan Plateau. The mean annual air temperature of the Qinghai-Tibetan Plateau varies between -3 C and -7 C and the minimum air temperature is lower than -37 C in short durations. The...

Northeastern China has the second largest expanse of permafrost in China, primarily known as Xing’an-Baikal permafrost. Located on the southeastern edges of the Eurasian cryolithozone, the permafrost is thermally unstable and ecologically sensitive to external changes. The combined impacts of climatic, environmental, and anthropogenic changes cause...

The two-phase closed thermosyphon (TPCT) is an effective heat transfer device decreasing the ground temperature around it in cold season, but not absorbing heat energy in warm season. In this paper, in order to research the efficiency of the TPCT applied to the embankment in permafrost regions, a three-dimension model for the TPCT embankment was pr...

To better understand the in-situ engineering conditions of frozen ground where the piers of Qinghai-Tibetan ±500kV Direct Current Transmission Line Project will be constructed; the direct shearing creep experiment for frozen silty clay, a kind of soil taken from Wudaoliang on the Qinghai-Tibetan Plateau and remodeled in different moisture contents...

Using the finite element method, thermal effects of the Chinese–Russian crude oil pipeline in permafrost regions were estimated under two construction modes (conventional burial and aboveground embankment), two thermal control techniques (bare and insulated pipe), and three climate conditions along the route (marked under the natural mean ground su...

The China–Russia Crude Oil Pipeline (CRCOP), 813mm in diameter, is designed to transport 603,000 barrels of Siberian crude oil per day across 1030km of frozen-ground. About 500 boreholes, with depths of 5 to 20m, were drilled and cored for analyses, and the frozen-ground conditions were evaluated. After detailed surveys and analyses of the permafro...

The purpose of this study is to estimate the stability of unprotected embankment in the warm and ice-rich permafrost (WIRP) region along the Qinghai–Tibet Railway. The estimation was based on field observations of the varying thermal regime under the unprotected embankments and of the ongoing settlement of this type of embankment. The observed data...

The purpose of this study is to investigate the settlement of the embankment constructed in warm and ice-rich permafrost (WIRP) region along the Qinghai–Tibetan Railway (QTR). In this investigation, an in-situ experiment for the thermal regime under this embankment and for the settlement of the embankment is proposed. The data illustrate that the t...

This study attempts to investigate the settlement characteristics of the unprotected embankment along the Qinghai–Tibet Railway. First, the investigation shows the observed data regarding the settlement of five adjacent unprotected embankment sections. Then, this data is estimated by using the fractal dimension to estimate the roughness of the emba...

As one part of the National Highway Network Planning in China, the Qinghai-Tibet Expressway (QTE) from Golmud to Lhasa will be built in the interior of the Qinghai-Tibet Plateau (QTP) across about 630 km of permafrost lands. Due to the problematic interactions between the engineering foundations and permafrost, the frozen-soil roadbed of the QTE wi...

Many researches and engineering practices about the Qinghai-Tibetan Highway have proved that the thermal stability of the roadbed is the key problem of the roadway stability in permafrost regions. Beginning with the concept of critical heights of roadway embankment in permafrost regions, we conducted an in-situ experiment along the Qinghai-Tibetan...

The permafrost with ice-rich content under the embankment of Qinghai–Tibet Railroad (QTR) is interestingly and increasingly warming, thus potentially posing an adverse effect on the operation of the railroad. This study first shows in-situ data to illustrate the essence of the warming permafrost. Experimental study for the compressible behavior of...

The warm and ice-rich frozen soil under an outside load will generate relatively large compression deformation which greatly influences the stability of roadbed. The compression tests of warm and ice-rich frozen soil show that under the constant load and variable temperatures, the compressibility at -1.5°C or -1.0°C is smaller than that at -0.5°C o...

In order to study the creep characteristics of the warm permafrost, a series of tests were carried out on the lateral pressure creep of the permafrost at Beiluhe test site along Qinghai-Tibet Railway at different water content and temperature. The test results indicate that the instantaneous deformation takes a large proportion in the whole deforma...

In order to study the strength character of warm and ice-rich frozen soil, a series of uniaxial compressive strength tests of frozen clays with water contents of 20%, 40%, 60%, 90%, 120% at temperatures of -0.3°C, -0.6°C, -0.9°C, -1.5°C, -5.0°C were conducted respectively. The test results indicate that: 1) The type of stress-strain curves for the...

The global warming is word actuality and puzzle. The prediction on the changes of southern limit of permafrost in Northeastern China was achieved by combining of equivalent-latitude and finite element models. The mean annual soil surface temperature (MASST) has a close linear correlation with the MAAT, if the air temperature increment assumed to be...

In order to study the mechanics characters of the warm and ice-rich permafrost beneath the embankment of Qinghai-Tibet Railway, a series of pressiometer tests were conducted in the Beiluhe test site of Qinghai-Tibet Railway. The tests results indicate that: the temperature of the permafrost beneath the embankment gets higher; unfrozen water of the...

Based on the field observational data of ground temperature and subgrade deformation in the transitional zone between embankment and cut at Beiluhe test section along the Qinghai-Tibet railway, this paper discusses the features of artificial permafrost table and subgrade deformation during the first five years of the construction. Analyses of the m...

In order to study the creep characteristics of warm and ice-rich frozen soil, a series of uniaxial creep tests of frozen clay with water content of 40%, 80%, 120% at temperature of -0.3°C, -0.5°C, -1.0°C were conducted respectively. It was shown that the creep process of the warm and ice-rich frozen soil was always attenuate; at the same temperatur...

According to the in-situ experiment results of embankment settlement and deformation at Beiluhe test site along Qinghai-Tibet Railway in permafrost regions, it was found that, even though the permafrost table under the embankment moved up after the railway was built, the embankment has suffered quite a lot of settlement, and the settlement was main...

By analyzing the temperature characteristics and damages of the experimental in-cuts roadbed at Beiluhe site of Qinghai–Tibetan railway, we find that it is difficult to ensure the stability of the in-cuts roadbed in warm permafrost regions if it is filled with coarse-grained soil with a low water content at the roadside slopes and bottom, and insul...

Based on the engineering practices of the embankment in permafrost regions of Qinghai-Tibet railway, and starting from the critical height of embankment, which indicates the thermal stability of the roadbed in permafrost regions, we conducted an in-situ experiment along Qinghai-Tibetan railway as well as a series of numerical analysis about the rea...

The heat transfer performance of hollow bricks with two kinds of thickness under the condition of vertical aperture was studied by steady comparison method. The results show: (1) for the system with the cold end being 0°C, it is cooled more quickly when the cold end is located on the top (mode I) than on the bottom (mode II); (2) when the temperatu...

In construction and maintenance of road engineering in cold regions, permafrost has been the mainly influencing factor in embankment stability. The cooling effect of the riprapped embankment on the soil beneath has been recognized. In this paper, the differences of the cooling effect and mechanism between the closed and open riprapped embankments h...

In permafrost regions of Qinghai–Tibetan plateau, the critical embankment height must be considered in the process of the construction of railway, especially for the global climatic warming. In this paper, the two-dimensional numerical analysis for the critical embankment height (for coarse-grained soil) has been performed by using the finite eleme...

In permafrost regions, the measures of constructing embankments or installing thermal insulations are in common use to keep the permafrost table under the roadways stable. However, the effectiveness of these measures depends on their adjustment to the mean annual ground temperature and the temperature amplitude in the permafrost under the roadway....

An in situ test was conducted to investigate the short-term mechanical behavior of frozen soils along the Qinghai–Tibet Highway, in China, using the pressuremeter. This paper uses the plane elasticity theory and the radial expansion equation of cylindrical hole in infinite elastic medium provided by Lamé to interpret the test data. The initial hori...

Test results show that the settlement process of model piles is mainly the rheological process of fmzen soil under shear loading. The settlement rate of model piles increases with increasing temperature of frozen soil, decreasing royghness of pile surface and increasing rigidity of pile foundation. As the water content of frozen soil reaches its sa...