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花岗岩风化料弃土快速堆填过程中不排水抗剪强度评估 被引量:5
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作者 詹良通 孙倩倩 +2 位作者 郭晓刚 陈锐 陈云敏 《岩土力学》 EI CAS CSCD 北大核心 2021年第1期50-58,共9页
沿海沿江城市地下开挖产生的工程渣土含泥量大、含水率高且较松散,主要运往渣土场进行堆填处置。由于产量巨大而处置场地有限,许多渣土场在运营过程中存在堆填速度快、缺乏排水设施、超高超库容堆填等问题,容易引发堆填体失稳事故。目... 沿海沿江城市地下开挖产生的工程渣土含泥量大、含水率高且较松散,主要运往渣土场进行堆填处置。由于产量巨大而处置场地有限,许多渣土场在运营过程中存在堆填速度快、缺乏排水设施、超高超库容堆填等问题,容易引发堆填体失稳事故。目前对于非饱和工程渣土堆体在快速堆填过程中的失稳机制认识尚不清晰,尤其是对这一过程中的高饱和度工程渣土强度增长规律缺乏足够的认识。以深圳红坳渣土场填料——花岗岩风化料(CDG)填土为研究对象,对不同初始饱和度土样进行三轴不排水不排气等向压缩和剪切试验,结果表明:非饱和CDG填土不排水抗剪强度随围压增大呈非线性增长,增长速率与试样初始饱和度密切相关;当土样压缩后的饱和度超过0.7,不排水强度随围压的增长速率显著降低。基于有效固结应力法的原理,结合Hilf孔压公式和修正剑桥模型,提出了一种工程渣土不排水抗剪强度估算方法,并通过与试验结果对比验证了该方法对初始饱和度高于0.6的CDG填土的适用性。利用该方法确定的不排水强度cu与正应力σn的关系可应用于高饱和度工程渣土快速堆填中的稳定性分析。 展开更多
关键词 工程渣土 渣土场 不排水抗剪强度 孔压分析 强度估算方法
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Characterization of Hydraulic Fracture with Inflated Dislocation Moving Within a Semi-infinite Medium 被引量:6
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作者 OUYANG Zhi-hua ELSWORTH Derek LI Qiang 《Journal of China University of Mining and Technology》 EI 2007年第2期220-225,共6页
Hydraulic fracturing is accompanied by a change in pore fluid pressure. As a result,this may be conveniently represented as inflated dislocation moving within a semi-infinite medium. Theory is developed to describe th... Hydraulic fracturing is accompanied by a change in pore fluid pressure. As a result,this may be conveniently represented as inflated dislocation moving within a semi-infinite medium. Theory is developed to describe the pore pressures that build up around an inflated volumetric dislocation migrating within a saturated porous-elastic semi-infinite medium as analog to hydraulic fracturing emplacement. The solution is capable of evaluating the system behavior of both constant fluid pressure and zero flux surface conditions through application of a superposition. Characterization of horizontal moving dislocation processes is conducted as an application of these techniques. Where the mechanical and hydraulic parameters are defined,a priori,type curve matching of responses may be used to evaluate emplacement location uniquely. Pore pressure response elicited at a dilation,subject to pressure control is of interest in representing hydraulic fracturing where leak-off is an important component. The effect of hydraulic fracturing on fracture fluid pressure is evaluated in a poroelastic hydraulic fracture model utilizing dislocation theory. A minimum set of dimensionless parameters are defined that describe the system. Pore fluid pressures recorded during hydraulic fracturing of a well in the San Joaquin Valley of Central California is examined using the proposed model. The estimated geometry of the hydraulic fracture is matched with reasonable fidelity with the measured data. 展开更多
关键词 volumetric dislocation: hydraulic fracturing dimensionless analysis pore pressure
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Influence of pore water pressure on upper bound analysis of collapse shape for square tunnel in Hoek-Brown media 被引量:5
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作者 黄阜 张道兵 +1 位作者 孙志彬 吴贲 《Journal of Central South University》 SCIE EI CAS 2011年第2期530-535,共6页
To investigate the effective shape of collapsing block in square tunnel subjected to pore water pressure,the analytical solution of detaching curve was derived using upper bound theorem of limit analysis with Hoek-Bro... To investigate the effective shape of collapsing block in square tunnel subjected to pore water pressure,the analytical solution of detaching curve was derived using upper bound theorem of limit analysis with Hoek-Brown failure criterion. The work rate of pore water pressure,which was regarded as an external rate of work,was taken into account in the framework of limit analysis. Taking advantages of variational calculation,the objective function with respect to detaching curve was optimized to obtain the effective shape of collapsing block for square tunnel. According to the numerical results,it is found that the varying pore water pressure coefficient only affects the height and width of the collapsing block,whereas the shape of collapsing block remains unchanged. 展开更多
关键词 upper hound theorem square tunnel pore water pressure variational calculation Hoek-Brown media
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Energy analysis of face stability of deep rock tunnels using nonlinear Hoek-Brown failure criterion 被引量:4
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作者 张佳华 李永鑫 许敬叔 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第8期3079-3086,共8页
The nonlinear Hoek-Brown failure criterion was introduced to limit analysis by applying the tangent method. Based on the failure mechanism of double-logarithmic spiral curves on the face of deep rock tunnels, the anal... The nonlinear Hoek-Brown failure criterion was introduced to limit analysis by applying the tangent method. Based on the failure mechanism of double-logarithmic spiral curves on the face of deep rock tunnels, the analytical solutions of collapse pressure were derived through utilizing the virtual power principle in the case of pore water, and the optimal solutions of collapse pressure were obtained by using the optimization programs of mathematical model with regard of a maximum problem. In comparison with existing research with the same parameters, the consistency of change rule shows the validity of the proposed method. Moreover, parametric study indicates that nonlinear Hoek-Brown failure criterion and pore water pressure have great influence on collapse pressure and failure shape of tunnel faces in deep rock masses, particularly when the surrounding rock is too weak or under the condition of great disturbance and abundant ground water, and in this case, supporting measures should be intensified so as to prevent the occurrence of collapse. 展开更多
关键词 tunnel face limit analysis failure criterion pore water pressure collapse pressure
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Numerical and theoretical verification of modified cam-clay model and discussion on its problems 被引量:1
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作者 戴自航 秦志忠 《Journal of Central South University》 SCIE EI CAS 2013年第11期3305-3313,共9页
Isotropic consolidation test and consolidated-undrained triaxial test were first undertaken to obtain the parameters of the modified cam-clay(MCC)model and the behavior of natural clayey soil.Then,for the first time,n... Isotropic consolidation test and consolidated-undrained triaxial test were first undertaken to obtain the parameters of the modified cam-clay(MCC)model and the behavior of natural clayey soil.Then,for the first time,numerical simulation of the two tests was performed by three-dimensional finite element method(FEM)using ABAQUS program.The consolidated-drained triaxial test was also simulated by FEM and compared with theoretical results of MCC model.Especially,the behaviors of MCC model during unloading and reloading were analyzed in detail by FEM.The analysis and comparison indicate that the MCC model is able to accurately describe many features of the mechanical behavior of the soil in isotropic consolidation test and consolidated-drained triaxial test.And the MCC model can well describe the variation of excess pore water pressure with the development of axial strain in consolidated-undrained triaxial test,but its ability to predict the relationship between axial strain and shear stress is relatively poor.The comparison also shows that FEM solutions of the MCC model are basically identical to the theoretical ones.In addition,Mandel-Cryer effect unable to be discovered by the conventional triaxial test in laboratories was disclosed by FEM.The analysis of unloading-reloading by FEM demonstrates that the MCC model disobeys the law of energy conservation under the cyclic loading condition if the elastic shear modulus is linearly pressure-dependent. 展开更多
关键词 modified cam-clay (MCC) model isotropic consolidation test consolidated-undrained triaxial test consolidated-drained triaxial test Mandel-Cryer effect energy conversation
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Energy analysis of stability on shallow tunnels based on non-associated flow rule and non-linear failure criterion 被引量:6
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作者 张佳华 王成洋 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第3期1070-1078,共9页
On the basis of upper bound theorem, non-associated flow rule and non-linear failure criterion were considered together.The modified shear strength parameters of materials were obtained with the help of the tangent me... On the basis of upper bound theorem, non-associated flow rule and non-linear failure criterion were considered together.The modified shear strength parameters of materials were obtained with the help of the tangent method. Employing the virtual power principle and strength reduction technique, the effects of dilatancy of materials, non-linear failure criterion, pore water pressure,surface loads and buried depth, on the stability of shallow tunnel were studied. In order to validate the effectiveness of the proposed approach, the solutions in the present work agree well with the existing results when the non-associated flow rule is reduced to the associated flow rule and the non-linear failure criterion is degenerated to the linear failure criterion. Compared with dilatancy of materials, the non-linear failure criterion exerts greater impact on the stability of shallow tunnels. The safety factor of shallow tunnels decreases and the failure surface expands outward when the dilatancy coefficient decreases. While the increase of nonlinear coefficient, the pore water pressure coefficient, the surface load and the buried depth results in the small safety factor. Therefore, the dilatancy as well as non-linear failure criterion should be taken into account in the design of shallow tunnel supporting structure. The supporting structure must be reinforced promptly to prevent potential mud from gushing or collapse accident in the areas with abundant pore water, large surface load or buried depth. 展开更多
关键词 non-associated flow rule non-linear failure criterion shallow tunnel upper bound theorem safety factor
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Three-dimensional consolidation deformation analysis of porous layered soft soils considering asymmetric effects 被引量:1
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作者 张治国 黄茂松 王卫东 《Journal of Central South University》 SCIE EI CAS 2014年第9期3639-3647,共9页
Long-term settlements for underground structures, such as tunnels and pipelines, are generally observed after the completion of construction in soft clay. The soil consolidation characteristic has great influences on ... Long-term settlements for underground structures, such as tunnels and pipelines, are generally observed after the completion of construction in soft clay. The soil consolidation characteristic has great influences on the long-term deformation for underground structures. A three-dimensional consolidation analysis method under the asymmetric loads is developed for porous layered soil based on Biot's classical theory. Time-displacement effects can be fully considered in this work and the analytical solutions are obtained by the state space approach in the Cartesian coordinate. The Laplace and double Fourier integral transform are applied to the state variables in order to reduce the partial differential equations into algebraic differential equations and easily obtain the state space solution. Starting from the governing equations of saturated porous soil, the basic relationship of state space variables is established between the ground surface and the arbitrary depth in the integral transform domain. Based on the continuity conditions and boundary conditions of the multi-layered pore soil model, the multi-layered pore half-space solutions are obtained by means of the transfer matrix method and the inverse integral transforms. The accuracy of proposed method is demonstrated with existing classical solutions. The results indicate that the porous homogenous soils as well as the porous non-homogenous layered soils can be considered in this proposed method. When the consolidation time factor is 0.01, the value of immediate consolidation settlement coefficient calculated by the weighted homogenous solution is 27.4% bigger than the one calculated by the non-homogeneity solution. When the consolidation time factor is 0.05, the value of excess pore water pressure for the weighted homogenous solution is 27.2% bigger than the one for the non-homogeneity solution. It is shown that the material non-homogeneity has a great influence on the long-term settlements and the dissipation process of excess pore water pressure. 展开更多
关键词 three-dimensional consolidation deformation porous layered soils asymmetric loads long-term deformation prediction transfer matrix method
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Analysis of Drilling Troubles in Kazhdumi Formation of Yadavaran Oilfield, Iran
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作者 Bo Min Xu Enxin +1 位作者 Jin Ruihuan Peng Nian 《China Oil & Gas》 CAS 2015年第2期21-25,共5页
Drilling crews of Sinopec have encountered a series of troubles when drilling a formation called kazhdumi of Yadavaran oilfield, Iran in the last few years. The formation is buried in the depth from 3300m to 3500m, ma... Drilling crews of Sinopec have encountered a series of troubles when drilling a formation called kazhdumi of Yadavaran oilfield, Iran in the last few years. The formation is buried in the depth from 3300m to 3500m, mainly including limestone, muddy limestone and some bituminous shale. Many microfissures exist in the formation and the equivalent density of formation pore pressure ranged from 1.19g/cm3 to 1.59g/cm3. Asphalt or heavy oil kicks occurred in drilling three wells in one and a half years, which contaminated the drilling fluid and made well killing difficult due to the kicks and lost circulation in open hole. Gas and hydrogen sulfide (the concentration is up to 40000ppm) were present in the wells, and finally two wells were completely abandoned and one partially losL which frustrated the drilling engineering seriously. By analyzing the data of &e drilled wells, the paper summarized the causes of the troubles, and put forward suggestions and conclusions that can serve as reference and guideline for drilling well in &is area in the future. 展开更多
关键词 lran Yadavaran Kazhdumi Formation DRILLING heavy oil hydrogen sulfide well control
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短时强降雨对排土场碎石土边坡稳定性的影响 被引量:13
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作者 郑开欢 罗周全 +3 位作者 罗成彦 汪伟 黄俊杰 秦亚光 《长安大学学报(自然科学版)》 EI CAS CSCD 北大核心 2016年第6期39-47,共9页
为了研究排土场层状碎石土边坡在短时强降雨条件下的入渗过程及稳定性,首先在SEEP/W中进行降雨条件下的饱和-非饱和渗流分析,得到不同时刻的瞬态孔隙水压力分布,然后将SEEP/W模拟结果分别导入SIGMA/W和SLOPE/W,进行孔压-应力耦合分析和... 为了研究排土场层状碎石土边坡在短时强降雨条件下的入渗过程及稳定性,首先在SEEP/W中进行降雨条件下的饱和-非饱和渗流分析,得到不同时刻的瞬态孔隙水压力分布,然后将SEEP/W模拟结果分别导入SIGMA/W和SLOPE/W,进行孔压-应力耦合分析和边坡稳定分析。最后通过对雨后不同时刻边坡内部孔隙水压力值变化情况的比较分析,探讨了雨后滑坡的发生机理。研究结果表明:强降雨对排土场碎石土边坡浅层影响最大,边坡浅层基质吸力随含水量的增大迅速降低,降低范围逐步向深部扩展,雨后基质吸力缓慢增大;降雨时排土场边坡渗流流速较大的区域主要集中在透水性最强的边坡浅层,当坡底存在弱透水层时,坡脚会很快产生涌水现象,涌水速度会逐渐增大,地下水位也会随之提高,雨后涌水减弱,地下水位降低;排土场边坡位移在降雨初期增加最快,之后增加速度趋缓,雨后会继续增大;降雨时排土场边坡安全系数快速下降,雨后随着边坡浅层水分继续下渗,边坡浅层下部含水量升高,最危险滑面位置会向基质吸力减小的边坡浅层下部发生转移,因此安全系数会继续降低至最小值,然后才开始缓慢增大。排土场层状碎石土边坡在短时强降雨作用下容易在雨后的一个较短时间内发生浅层滑坡。 展开更多
关键词 道路工程 排土场 强降雨 饱和-非饱和渗流 基质吸力 -应力耦合分析 安全系数
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