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Upper bound solution to seismic active earth pressure of submerged backfill subjected to partial drainage

《结构与土木工程前沿（英文）》 2021年第15卷第6期页码 1480-1493 doi: 10.1007/s11709-021-0776-y

摘要： In waterfront geotechnical engineering, seismic and drainage conditions must be considered in the design of retaining structures. This paper proposes a general analytical method to evaluate the seismic active earth pressure on a retaining wall with backfill subjected to partial steady seepage flow under seismic conditions. The method comprises the following steps: i) determination of the total head, ii) upper bound solution of seismic active earth thrust, and iii) deduction for the earth pressure distribution. The determination of total head h(x,z) relies on the Fourier series expansions, and the expressions of the seismic active earth thrust and pressure are derived by using the upper bound theorem. Parametric studies reveal that insufficient drainage and earthquakes are crucial factors that cause unfavorable earth pressure. The numerical results confirm the validity of the total head distribution. Comparisons indicate that the proposed method is consistent with other relevant existing methods in terms of predicting seismic active earth pressure. The method can be applied to the seismic design of waterfront retaining walls.

关键词： seismic active earth pressure partial seepage flow pore pressure anisotropy upper bound theorem

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Deviation correction strategy for the earth pressure balance shield based on shield–soil interactions

《机械工程前沿（英文）》 2022年第17卷第2期 doi: 10.1007/s11465-022-0676-4

摘要： The control system presently used in shield posture rectification is based on driver experience, which is marginally reliable. The study of the related theory is flawed. Therefore, a decision-making approach for the deviation correction trajectory and posture rectification load for an earth pressure balance (EPB) shield is proposed. A calculation model of posture rectification load of an EPB shield is developed by considering the interactions among the cutter head, shield shell, and ground. The additional position change during the shield attitude correction is highlighted. The posture rectification loads and shield behaviors results can be solved by the proposed method. The influences of the stratum distribution (i.e., bedrock height in the upper-soft and lower-hard strata) on shield behaviors and posture rectification loads are analyzed. Results indicated that the increase of pitch angle in the upper-soft and lower-hard strata causes a sharp rise in vertical displacement. The bedrock height increases the magnitudes of the required posture rectification moments when h_r/D > 0.5. For a tunnel with h_r/D ≤ 0.5, the variation of h_r/D has little effect on the posture rectification moments. Finally, the posture rectifying curves based on the theoretical model are compared with the target ones based on the double circular arc interpolation method. The required results can be obtained regardless of the soil–rock compound stratum distribution. The maximum rectification moment in the rock layer is almost 12.6 times that in the soil layer. Overall, this study provides a valuable reference for moment determination and the trajectory prediction of posture rectification in compound strata.

关键词： additional position change deviation correction trajectory earth pressure balance shield mechanical model posture rectification

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Experimental study on the stratum applicability and mechanisms of bubble–slurry for earth pressure balance

《结构与土木工程前沿（英文）》页码 1387-1399 doi: 10.1007/s11709-023-0005-y

摘要： Soil conditioning is essential for addressing the stratum applicability problem of earth pressure balance (EPB) shields. Under high water pressures, EPB shields spew water and soil when excavating coarse-grained strata. Typically, foam combined with polymers and slurry is used to solve spewing. However, in current techniques, slurry, foam, and the other agents are mixed with soil separately, their synergistic effect is seldom realized. In this study, an anionic surfactant was used to foam in bentonite slurry to form bubble–slurry to maximize the synergy between bubbles and slurry. The slump, volume stability, and permeability test of bubble–slurry-conditioned sand was conducted to examine the conditioning effect, and the stratum applicability of bubble–slurry was determined from the perspective of permeability. It was found that the conditioning effect of bubble–slurry in coarse gravel soil was excellent and could expand the applicability of EPB shields. The main stabilization mechanism of bubble–slurry is that bentonite particles provide a space barrier for bubbles. And three seepage modes of bubble–slurry-conditioned sand were innovatively defined, and the occurrence conditions of the three seepage modes were analyzed according to the permeability coefficient of sand, initial dynamic shear force of bubble–slurry, and hydraulic gradient.

关键词： EPB shield bubble–slurry soil conditioning stability permeability

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Seismic stability of earth slopes with tension crack

Yundong ZHOU, Fei ZHANG, Jingquan Wang, Yufeng GAO, Guangyu DAI

《结构与土木工程前沿（英文）》 2019年第13卷第4期页码 950-964 doi: 10.1007/s11709-019-0529-3

摘要： Cracks at the crest of slopes frequently occur during earthquakes. Such cracks result from limited tension strength of the soil. A tension cut-off in Mohr-Coulomb shear strength can represent this limited strength. Presented is an extension of variational analysis of slope stability with a tension crack considering seismicity. Both translational and rotational failure mechanisms are included in a pseudo-static analysis of slope stability. Developed is a closed-form to assess the seismic stability of slopes with zero tensile strength. The results indicate that the presence of the tension crack has significant effects on the seismic stability of slopes, i.e. leading to small value of the yield acceleration. Considering soil tension strength in seismic slope analysis may lead to overestimation on the stability, as much as 50% for vertical slopes. Imposing tension crack results in transit of the critical failure mode to a straight line from a log-spiral, except for flat slopes with small soil cohesion. Under seismic conditions, large cohesion may increase the depth of crack, moving it closer to the slope.

关键词： slope stability tension crack limit equilibrium seismic effect

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Coulomb-type solutions for passive earth pressure with steady seepage

WANG Junjie, CHAI Hejun, LIN Xin, XU Jiamei

《结构与土木工程前沿（英文）》 2008年第2卷第1期页码 56-66 doi: 10.1007/s11709-008-0001-2

摘要： Present paper deals with the computing of passive earth pressure acting on the vertical rigid retaining wall supporting the soil mass subjected to water seepage. The basic assumptions of Coulomb’s theory and the 2-dimensional steady flow function are used. Three Coulomb-type solutions for the passive earth pressures are presented for the walls provided with three different drainage systems respectively. Based on the general solutions, the variations of the critical inclination of the failure surface and the coefficient of passive earth pressure with increasing the effective friction angle of the soil mass, the soil/structure friction angle, and the water/soil unit weight ratio are discussed. Two tables with values of the coefficients of passive earth pressure for Cases 1 and 3 respectively are also presented.

关键词： function coefficient Coulomb-type effective friction different drainage

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Experimental study on working parameters of earth pressure balance shield machine tunneling in soft ground

ZHU Hehua, LIAO Shaoming, XU Qianwei, ZHENG Qizhen

《结构与土木工程前沿（英文）》 2008年第2卷第4期页码 350-358 doi: 10.1007/s11709-008-0051-5

摘要： Deep sedimentary deposits of soft clays are widely distributed in coastal areas as well as many interior major cities in China. In order to study the stratum adaptability of earth pressure balance (EPB) shield machine tunneling in such types of soft ground, model tests of tunneling excavation, using the running tunnel of the Shanghai Metro Line M8 as a background, are carried out with different over burden ratios, opening rates of cutter head, driving speeds and rotation speeds of screw conveyor. Based on the test results, the interrelationships between chamber pressure and mucking efficiency, mucking rate and driving speed, thrust force and torque are obtained. The influences of tunnel depth, opening rate of cutter head and driving speed on thrust force and torque are revealed. Such findings can not only facilitate establishing relationships between shield working parameters and soil properties, but also serve as a guide for the design and construction of shield tunnel in soft ground.

关键词： construction different coastal conveyor excavation

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Semi-active fuzzy control of Lali Cable-Stayed Bridge using MR dampers under seismic excitation

Sajad JAVADINASAB HORMOZABAD, Amir K. GHORBANI-TANHA

《结构与土木工程前沿（英文）》 2020年第14卷第3期页码 706-721 doi: 10.1007/s11709-020-0612-9

摘要： Seismic control of cable-stayed bridges is of paramount importance due to their complex dynamic behavior, high flexibility, and low structural damping. In the present study, several semi-active Fuzzy Control Algorithms (FCAs) for vibration mitigation of Lali Cable-Stayed Bridge are devised. To demonstrate the efficiency of the algorithms, a comprehensive nonlinear 3-D model of the bridge is created using OpenSees. An efficient method for connecting MATLAB and OpenSees is devised for applying FCAs to the structural model of the bridge. Two innovative fuzzy rule-bases are introduced. A total of six different fuzzy rule-bases are utilized. The efficiency of the FCAs is evaluated in a comparative manner. The performance of fuzzy control systems is also compared with a sky-hook and a passive-on system. Moreover, the sensitivity of efficiency of control systems to the peak ground acceleration is evaluated qualitatively. In addition, the effect of time lag is also investigated. This study thoroughly examines the efficiency of the FCAs in different aspects. Therefore, the results can be regarded as a general guide to design semi-active fuzzy control systems for vibration mitigation of cable-stayed bridges.

关键词： semi-active control Fuzzy Control Algorithm cable-stayed bridge MR damper Lali Bridge

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Identification of abnormal operating conditions and intelligent decision system

Xiuliang LI, Junjie JIANG, Hongye SU, Jian CHU

《机械工程前沿（英文）》 2011年第6卷第4期页码 456-462 doi: 10.1007/s11465-011-0224-0

摘要：

In earth pressure balance (EPB) shield construction, the “plastic flow state” is difficult to form using the soil dug in the capsule because it can cause three abnormal operating conditions, including occlusion, caking in the capsule, and spewing at the outlet of the dump device. These abnormal operating conditions can, in turn, trigger failure in tunneling, cutter-device damage, and even catastrophic incidents, such as ground settlement. This present paper effectively integrates the mechanism of abnormal operating conditions and knowledge of soil conditioning, and establishes a uniform model of identifying abnormal conditions and intelligent decision support system based on the belief rule-base system. The model maximizes knowledge in improving the soil, construction experience, and data to optimize the model online. Finally, a numerical simulation with specific construction data is presented to illustrate the effectiveness of the algorithm.

关键词： earth pressure balance (EPB) shield machine soil pressure cabin abnormal operating condition belief rule-base system

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高压多晶X射线衍射方法的发展及其在地球深部研究中的应用 Review

张莉, 苑洪胜, 孟悦, 毛河光

《工程（英文）》 2019年第5卷第3期页码 441-447 doi: 10.1016/j.eng.2019.02.004

摘要：

下地幔占地球体积一半以上。在高温高压下对下地幔真实组分所开展的矿物学和岩石学实验是了解深部地幔演化过程的必要途径。激光加热的金刚石对顶压砧（laser-heated diamond anvil cell, LHDAC）是开展这类高温高压实验最常用的工具，实验产物通常包括从上百纳米到数微米尺寸不一的大量晶粒所组成的多相集合体。这些下地幔相的晶体结构往往不能在卸压后保存下来，因此必须对它们进行原位表征。相对于同步辐射光源设备中可用的聚焦X射线光斑尺寸（3~5 μm），晶粒尺寸要小一个量级，所得到的X射线衍射（X-ray diffraction, XRD）图谱通常显示为衍射斑点和衍射环的混合。由于多相衍射峰重叠严重，粉晶X射线衍射法无法对新相和弱相进行鉴定，因此采用传统XRD技术测定高温高压下多相混合物非常困难。我们最近在高压研究中所发展的同步辐射多晶X射线衍射法可以通过测定多相组合中成千上百个晶粒各自的晶面取向，使多相体系中单晶的指标化成为可能。一旦完成指标化，多晶混合物中的每一个晶粒都可以看作是单晶。因此，我们可以同时确定多相体系中新相和弱相的晶体结构。随着这一新方法的发展，我们开辟了深下地幔高温高压条件下的结晶学新领域。本文阐述了多相体系研究中的关键技术挑战，并通过高压多相X射线衍射法的成功应用实例，论证了该方法的独特能力。

关键词：高压同步辐射X射线多晶金刚石对顶压砧矿物学岩石学地球内部

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Experimental study on concrete box culverts in trenches

Baoguo CHEN, Junjie ZHENG, Jie HAN

《结构与土木工程前沿（英文）》 2009年第3卷第1期页码 73-80 doi: 10.1007/s11709-009-0008-3

摘要： Concrete box culverts are widely used in expressways in mountain areas. Many problems frequently take place due to improperly estimated vertical earth pressures on culverts. The prevailing Chinese General Code for Design of Highway Bridges and Culverts (CGCDHBC) stipulates the computation of the design load on culverts primarily based on the linear earth pressure theory, which cannot accurately describe the variation of the vertical load on culverts in trenches. In this paper, a full-scale experiment and numerical simulation were conducted to evaluate the variation of vertical earth pressures on culvert and soil arching in backfill. The variations of foundation pressure and settlement were also analyzed. The result revealed that the soil arch forms when the backfill on the culvert reaches a certain height. The soil arching effect reduces the stress concentration on the crown of the culvert but it is unstable. The vertical earth pressure on top of the culvert is significantly different from that recommended by the CGCDHBC

关键词： culvert vertical earth pressure soil arch full-scale experiment numerical simulation

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锚碇沉井基础施工期安全监控技术

冯兆祥,王锦国,王建

《中国工程科学》 2010年第12卷第4期页码 68-72

摘要：

针对泰州大桥南锚沉井基础的结构特点和施工方法，设计了施工安全监控方案。施工期监测成果分析表明：沉井下沉初期沉井底部刃脚附近水平方向的拉应力较大，将此项物理量作为下沉的控制指标，有效指导了沉井施工；侧壁土压力分布随入土深度呈先增加后减小规律。

关键词：沉井控制指标下沉侧壁土压力

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DX桩桩周土应力场分布的模型试验研究

唐松涛,陈立宏,袁希雨

《中国工程科学》 2012年第14卷第1期页码 105-112

摘要：

通过室内小比尺的模型试验，可以进一步为确定DX桩沉降计算公式提供必要的依据。在小型模型试验箱中，通过采用杠杆加砝码的装置对22 mm桩径的DX桩在砂土中进行研究，测定单桩的桩顶荷载-桩顶位移曲线，确定承载力，并与相同情况下的直孔桩进行对比；同时，利用微型土压力盒测定土中应力变化，研究荷载在土中的传递规律。试验结果表明，DX桩的承载力及沉降特性明显优于直孔桩；承力盘在上部和下部时，DX桩尽管承载力相差不大，但是盘在下部时会增大桩端附近土体的应力；两个承力盘的DX桩，两盘受力比较一致，且盘受力的影响范围，在竖

关键词： DX桩土压力盒应力量测

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Effect of earth reinforcement, soil properties and wall properties on bridge MSE walls

《结构与土木工程前沿（英文）》 2021年第15卷第5期页码 1209-1221 doi: 10.1007/s11709-021-0764-2

摘要： Mechanically stabilized earth (MSE) retaining walls are popular for highway bridge structures. They have precast concrete panels attached to earth reinforcement. The panels are designed to have some lateral movement. However, in some cases, excessive movement and even complete dislocation of the panels have been observed. In this study, 3-D numerical modeling involving an existing MSE wall was undertaken to investigate various wall parameters. The effects of pore pressure, soil cohesion, earth reinforcement type and length, breakage/slippage of reinforcement and concrete strength, were examined. Results showed that the wall movement is affected by soil pore pressure and reinforcement integrity and length, and unaffected by concrete strength. Soil cohesion has a minor effect, while the movement increased by 13–20 mm for flexible geogrid reinforced walls compared with the steel grid walls. The steel grid stresses were below yielding, while the geogrid experienced significant stresses without rupture. Geogrid reinforcement may be used taking account of slippage resistance and wall movement. If steel grid is used, non-cohesive soil is recommended to minimize corrosion. Proper soil drainage is important for control of pore pressure.

关键词： mechanically stabilized earth walls precast concrete panels backfill soil finite element modeling earth reinforcement

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城市规划中抗震减灾的新构想——“强震发生断层”的发现和启示

李玶,杨美娥,赵东芝

《中国工程科学》 2007年第9卷第7期页码 1-6

摘要：

不是所有的活断层都会发生破坏性地震（５～６级以上），只有其中的极少数在未来数十年、数百年内有可能发生强震，特称之为强震发生断层。这种断层有一定宽度，一般为数米、数十米到数百米或更多。在断层范围内，地震波峰值加速度陡增，烈度可增加２°～３°或更多，抗震设计很困难。断层范围外，烈度随着离震中距离的增大而减弱，抗震按常规设计即可；台湾集集地震的观测数据却提示，0.15g 的抗震设计，竟能抵御 0.5g 的破坏，抗震设计采用的地震动参数，蕴藏着巨大的抗震潜能，这使建筑物抗震达到人员零死亡的目标成为可能。强震发生断层的识别和圈定，从地震构造学的角度解决了地震预报的时、空、强三个要素。城市规划中在采用诸多有关抗震规范时，应考虑强震发生断层的有无及其增震作用，提请有关部门对规范作必要的修改和补充。

关键词：城市规划抗震减灾活断层强震发生断层强震发生断层的增震作用

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极端条件下材料化学和输运性质的第一原理研究 Review

John S. Tse

《工程（英文）》 2019年第5卷第3期页码 421-433 doi: 10.1016/j.eng.2019.01.008

摘要：

地球是一个动态系统。从常温常压到地核的360 GPa 和6600 K，地球的热力学状态随着深度的变化而发生很大变化。因此，地球成分（如硅酸盐和碳酸盐矿物）的物理和化学性质受其所处环境的显著影响。在过去的30 年中，在极端条件下的材料表征的实验技术和理论模拟方法都取得了巨大的进步。这些进步提升了我们对矿物特性的理解，这对于充分认识这个星球的形成及其生命起源至关重要。本文回顾了用于预测极端条件下材料性质的最新计算技术，本研究仅限于应用第一原理分子动力学（first principle molecular dynamics, FPMD）方法研究与地球科学相关的化学和热力学输运过程。

关键词：高压高温地幔分子动力学密度泛函方法输运性质化学反应