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Xu G.-L.,Wuhan University | Ma Y.,Wuhan University | Ma Y.,Central Southern Geotechnical Design Institute Co. | Zhang J.-Q.,Wuhan City Construction Project Design Review Office | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2014

The geological conditions of groundwater can be changed by the artificial retaining structures and waterproof curtains for underground engineering. In addition, change of groundwater level will impact the construction or operation of underground engineering. Much attention is paid to the dewatering and land subsidence problems, but little paid to the impact of rising of groundwater level. Tokyo has the most complicated underground engineering system in the world. The groundwater level had decreased before 1970 and has risen after 1970. The mean rising is 15 m, while the largest rising, about 60 m, is recorded in the central ward. The impacts on the existing substructures, such as leakage, floating and corrosion problems, are analyzed. It is concluded that it is more important to predict and control the groundwater under operation than that during the construction period because the hazards induced by the rising of water level are more urgent, and it is much more difficulty to take countermeasures. The lessons are significant for the development and utilization of underground space, especially in the coastal cities, inland basins and northern regions in China.


Qu R.-F.,Wuhan University | Qu R.-F.,Wuhan Metro Group Co. | Xu G.-L.,Wuhan University | Wang J.-F.,Wuhan Metro Group Co. | And 4 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2014

The shear strength indices of deep foundation pits in Wuhan area are generally acquired through direct shear tests. They are simple and locally applicable and fails to simulate the natural state of soils. Thus, the soil strength parameters obtained have certain limitation, and the correlations of physical and mechanical properties are also vague. In order to study the correlations of physical and mechanical properties of typical soft soils in Wuhan, based on the deep excavation of soft soils in Wuhan area, four hundred groups of data from 10 projects in Wuhan are adopted. Physical and mechanical parameters of soft soils in Wuhan are studied. Combined with the traditional methods of mathematical analysis, the engineering geological characteristics are investigated, and the correlations between the physical and mechanical parameters and their indices are analyzed. The results show the physical indices of typical soft soils, such as natural density, dry density, liquid limit, plastic limit and saturation, are in normal distribution. The statistical distribution of shear strength indices indicates that the normal distribution of physical parameters will change with different experimental conditions for different soils.


Yang Y.,Central Southern Geotechnical Design Institute Co. | Wang K.,Central Southern Geotechnical Design Institute Co. | Liu Y.-X.,Central Southern Geotechnical Design Institute Co. | Wei Z.-P.,Central Southern Geotechnical Design Institute Co. | Li J.-C.,Nanjing University of Technology
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2014

Through the analysis and reinforcement design case of a deep silt excavation accident, it is indicated that the selection of excavation structures is very important. With regard to the distinct thixotropic and rheological characteristics and poor engineering mechanical properties of the marine sedimentary silt, the safety reliability and practicability of the excavation structures should be assessed. The possible danger should be predicted. The relevant plan and design measures should be formulated.


Ming-ming Y.,Wuhan University | De-shan C.,Wuhan University | Tian-qi W.,Central Southern Geotechnical Design Institute Co. | Shu-sheng Y.,Central Southern Geotechnical Design Institute Co.
Electronic Journal of Geotechnical Engineering | Year: 2015

With strong regional differences, the shear strength and index of correlation of sulfate salty soil vary, and they cannot be all-purpose. Through laboratory direct shear test, we choose the common salty soil in northwest section of Meng-xi railway under construction to research the consequences of sulfate salty content to the salty soil from Macro-Micro analysis, to seek the optimal salt content, and so that it provides theoretical basis for upgrading strength of salty soil for engineering construction. The test shows: On the macro, the optimal salt content of sulfate for salty soil varies from 4.4%~6.7%; on the micro, it varies from 5.7%~6.5%. © 2015 ejge.


Li Y.Y.,Hubei University | Sun R.L.,Hubei University | Chen R.Q.,Central Southern Geotechnical Design Institute Co.
Applied Mechanics and Materials | Year: 2013

Hydraulic conductivity (K) and scale effects in basalt in the dam area of Xiluodu hydroelectric station were investigated by three kinds of field hydraulic tests with different test scale, 2608 water pressure tests in single borehole, 54 water seepage tests in adit and groundwater tracer test. Statistical results show the high heterogeneity of fractured rock and K difference between two neighboring test intervals are often more than two orders of magnitude. However, there is a strong decreasing trend of hydraulic conductivity with the increase of vertical depth. Moreover, these three kinds of hydraulic test results demonstrate that hydraulic conductivity increases with the increase of test scale in heterogeneous basalt and the heterogeneous degree of K decreases with the increase of test scale. K from water seepage test in adit, with the test scale of 1-2 m, is dispersed from 0.00024 m/d to 3.46 m/d. K from water pressure test in single borehole, with the test scale of 4-7 m, is 0.0002-1.04 m/d. K from groundwater tracer test, with the test scale of 70-145 m, is concentrated between 0.46 m/d and 2.1 m/d. High heterogeneity of fractured rock and multi-level of fractures are thought as the major reason resulted in scale effects of hydraulic conductivity. © (2013) Trans Tech Publications, Switzerland.


Ma Y.,Wuhan University | Ma Y.,Central Southern Geotechnical Design Institute Co. | Qu R.-F.,Wuhan University | Zhou X.-T.,Wuhan University | And 3 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

n order to study the influence of the parameters of strengthened soils in passive zone of excavations on the lateral displacement of supporting structures in soft soil ground, based on a typical excavation in Wuhan, a finite difference model is established by the FLAC two-dimensional numerical simulation method. Then, the calculated results of CX6 are compared with the field data to verify the rationality and accuracy of the numerical model. The distribution laws of stress on piles and lateral displacement of supporting structure at different measuring points are in consistency, which reflects the correctness of the measured data. The effects of the depth, width and shape in passive zone on the lateral deformation of the supporting structures are studied. The calculated results are compared with the field data to verify the rationality and accuracy of the numerical model. The better agreement of filed data and the numerical simulation analysis shows that the numerical simulation can be used to analyze the actual deformation laws of the supporting structure. The multi-stair improvement has obvious advantages in passive zone compared with other forms, and it shows great application value in Wuhan soft soil layer areas. The effects of strengthened soils in passive zone on the lateral deformation of the supporting structures are obvious. The effects of the depth and width in passive zone exist a valid range. When those parameters exceed a certain value, the increasing rate of the reinforcement effects will be very little. When the width and depth of the improvement are approximately equal, the optimum reinforcement effect can be obtained.


Ma Y.,Wuhan University | Ma Y.,Central Southern Geotechnical Design Institute Co. | Li S.,Central Southern Geotechnical Design Institute Co. | Xu G.-L.,Wuhan University | And 4 more authors.
Yantu Lixue/Rock and Soil Mechanics | Year: 2014

Taking the Zhonghai International Building ultra deep foundation pit in Wuhan Yangtze River I terrace as an object, the shear strength index of soft soil is obtained by using static pressure sampler, combining indoor soil test which include direct shear test (qq), consolidated quick shear test (cq), triaxial consolidated undrained test (cu) and triaxial unconsolidated undrained test (uu), and using the principle of mathematical statistics and comparing with qq shear strength index obtained by core tube. Meanwhile, a simulation analysis of Zhonghai International Building ultra deep foundation pit is carried out by 3D finite element software Midas GTS to study the variation of horizontal displacements of diaphragm wall and earth pressures of stratum mainly, and it is compared with measured data. It is found that using static pressure sampler for the perturbations of stratum is smaller than that of core tube. The shear strength index obtained by the static pressure sampler is more reliable. When selecting core tube shear strength index, the horizontal displacement of diaphragm wall and earth pressure of stratum are more closer to the measured data, cq index is followed. Proposal to select cu index for the first level excavation, and select cq index for the second and the third level excavations. ©, 2014, Academia Sinica. All right reserved.


Ma Y.,Wuhan University | Ma Y.,Central Southern Geotechnical Design Institute Co. | Wei Z.-Y.,Wuhan University | Wei Z.-Y.,Hydro China Huadong Engineering Corporation | And 3 more authors.
Yantu Lixue/Rock and Soil Mechanics | Year: 2014

With the development of foundation pit scale toward larger and deeper, the traditional single pile, the pile anchor supporting structure, pile brace are subject to certain restrictions, in the case of higher control requirements in the deformation and which should not be used within support and anchor, double-row piles can play a better role. Double-row piles consist of two rows of parallel retaining piles, top beam and connecting beam formed a space envelope system. High stiffness, good stability, small deformation and benefit for erect excavation are the strengths, so double-row piles are widely used in deep foundation pit engineering. In the new specification Technical Specification for Engineering of Foundation Excavation (DB42/T159-2012) increases the foundation retaining structure with double-row piles in related chapters. On the basis of the double-row piles calculation model proposed in the new pit specification of Hubei province, a simple, practical design and calculation software of double-row piles for foundation pit (hereinafter referred DESDROP) has been developed by VB.NET. The research and development of this software is to cooperate with new rules for implementation. The displacement, internal force and stability of the double-row piles are analyzed by the software; and the soil pressure, displacement, bending moment, shear force diagram also can be seen through the query result under any working conditions. The software has been applied to Jindimingjun foundation pit engineering. The results show that the operation speed of DESDROP software is fast, calculation results can meet the needs of the double-row piles supporting design.

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