土钉与锚杆联合支护在深基坑工程中的应用

结合深圳市星海阁办公楼的工程实例,从周边环境对深基坑支护的特殊要求及复杂的地质条件出发,论述了采用土钉与锚杆联合支护形式的依据.介绍了在深基坑支护施工中采取的具体措施后期效果.同时分析了这种联合支护结构形式的力学特点,通过将两者联合使用,可实现锚杆支护结构水平侧移小和土钉支护结构受力合理的优点.且土钉与锚杆联合支护,使得上部锚杆和中下部的土钉墙两者形成了统一的受力整体,共同抵抗荷载和变形.     

深圳市某建筑深基坑支护滑塌事故剖析

以深圳某建筑深基坑滑塌为例,在现场实物和相关资料调查的基础上,从基坑支护的设计、施工、监测以及质量安全管理等方面对基坑滑塌事故的原因进行了较为全面的分析和探讨,认为导致该基坑支护工程滑塌的主要原因是土钉和锚索抗拔力不足.最后针对目前深基坑工程中普遍存在的问题提出了加强设计方案的审查、加强施工管理、加强土钉墙研究的建议.     

浙江江山石鼓水库除险加固工程技术措施

根据浙江江山石鼓水库大坝的结构构造特点、水库地质条件以及水库病险原因与状况，制定出一套科学完善的病险水库除险加固工程技术措施和施工操作规程，对病险水库进行了全面彻底治理，并取得良好效果。详细介绍了工程病险状况，除险加固方案设计，施工工艺及操作规程，加固效果检测及评价等。     

Limitations of suction‐controlled triaxial tests in the characterization of unsaturated soils

Behavior of unsaturated soils is influenced by many factors, and the influences of these factors are usually coupled together. Suction‐controlled triaxial (SCTX) tests are considered to allow researchers to investigate influences of individual variables on unsaturated soils under specified stress path with controls of stresses, pore water, and air pressures. In the past 50 years, SCTX testing method has been established as a standard approach to characterize constitutive behavior of unsaturated soils. Most important concepts for modern unsaturated soil mechanics were developed upon results from the SCTX tests. Among these, one of the most important contributions in the constitutive modeling of elasto‐plastic behavior for unsaturated soils is the Barcelona basic model (BBM) proposed by Alonso et al. in 1990. The BBM successfully explained many features of unsaturated soils and received extensive acceptance. However, the SCTX tests are designed based upon the divide‐and‐conquer approach in which an implicit assumption is used: soil behavior is stress‐path independent. However, it is well‐established that unsaturated soil behavior is elasto‐plastic and stress‐path dependent. It is found that the SCTX tests in fact cannot control the stress path of an unsaturated soil during loading. This incapability, in combination with complicated loading/collapse behavior of unsaturated soils, makes the SCTX tests for characterizing unsaturated soil questionable. This paper discusses the limitations of the SCTX tests in the characterization of unsaturated soils. A possible solution to the problem was proposed based on a newly developed modified state surface approach. The discussions are limited for isotropic conditions. Copyright © 2015 John Wiley & Sons, Ltd.     

Modeling the 2D behavior of dry‐stone retaining walls by a fully discrete element method

The dry‐stone retaining walls (DSRW) have been tipped as a promising solution for sustainable development. However, before recently, their behavior is relatively obscure. In this study, discrete element method (DEM) approach was applied to simulate the plane strain failure of these walls. A commercial DEM package (PFC2D™) was used throughout this study. The authors used a fully discrete approach; thus, both the wall and the backfill were modeled as discrete elements. The methodology for obtaining the micromechanical parameters was discussed in detail; this includes the three mechanical sub‐systems of DSRWs: wall, backfill and interface. The models were loaded progressively until failure, and then the results were compared with the full‐scale experimental results where the walls were loaded, respectively, with hydrostatic load and backfill. Despite its complexity and its intensive calculation time, DEM model can then be used to validate a more simplified approach. Copyright © 2015 John Wiley & Sons, Ltd.     

Retaining wall optimization using interior search algorithm with different bound constraint handling

Along with the applicability of optimization algorithms, there are lots of features that can affect the functioning of the optimization techniques. The main purpose of this paper is investigating the significance of boundary constraint handling (BCH) schemes on the performance of optimization algorithms. To this end, numbers of deterministic and probabilistic BCH approaches are applied to one of the most recent proposed optimization techniques, named interior search algorithm (ISA). Apart from the implementing different BCH methods, a sensitivity analysis is conducted to find an appropriate setting for the only parameter of ISA. Concrete cantilever retaining wall design as one of the most important geotechnical problems is tackled to declare proficiency of the ISA algorithm, on the one hand, and benchmark the effect of BCH schemes on the final results, on the contrary. As results demonstrate, various BCH approaches have a perceptible impact on the algorithm performance. In like manner, the essential parameter of ISA can also play a pivotal role in this algorithm's efficiency. Copyright © 2017 John Wiley & Sons, Ltd.     

Tectono-sedimentary control on modern sand deposition on the forebulge of the Western Taiwan Foreland Basin

Whether the formation of the isolated sand body deposition in the forebulge area of a foreland basin system is structure- or deposition-controlled has puzzled geologists for decades, although sand body deposition is generally believed to be indicative of the position of the flexural forebulge in a foreland basin. The formation of a modern sand body in the forebulge area is thus examined by multi-scale geophysical observations based on combined reflection seismic profiles and compressed high-intensity radar pulse (CHIRP) profiles across the sand deposition along the forebulge of the Western Taiwan Foreland Basin (WTFB), which is a Late Miocene-present foreland basin in the overfilled stage. These profiles suggest that the accumulation of the sand deposits along the forebulge of the WTFB is not directly associated with forebulge faultings. The relief map of the forebulge deposit substratum shows a northwestward tilting slope, and the isopach of the forebulge sand body indicates that a large part of the sand body accumulated along the axis of the Taiwan Strait and the subdued forebulge of the WTFB. The difference between the prevailing directions of tidal currents between the Taiwan Strait and the East China Sea reflects the probable sedimentary influence of the cratonward migrating fold-thrust belt within a foreland shelf. We suggest that the formation and distribution of the sand deposits along the forebulge of the WTFB are generally controlled not only by the transverse downslope sedimentation but also longitudinal hydrodynamic processes at distal parts of the foreland basin. Our explanation provides a plausible tectono-sedimentary cause of the sand body deposition in the forebulge area in an overfilled foreland basin. The sedimentary dynamics of the sand body in the Taiwan Strait may be applicable for understanding the formation of isolated sand bodies in the distal part of the Cretaceous Western Interior Foreland Basin.     

纪念中国大陆科学钻探实施15周年、国际大陆科学钻探委员会成立20周年

大陆科学钻探是“入地”的重要手段,是“深入地球内部的望远镜”。中国大陆科学钻探事业开展15周年以来,取得重要进展,获得全球地学界的高度关注,特别是2001年实施的中国第一口大陆科学深钻 （5158m）,成果辉煌,影响巨大。继后,又开展了青海湖环境科学钻探、松辽盆地白垩纪科学钻探、柴达木盐湖环境资源科学钻探,汶川地震断裂带科学钻探以及中国大陆科钻资源集成计划,总共钻进约 35km,显示了中国科学钻探方兴未艾的景象。为纪念国际大陆科学钻探20周年（1996~2016）和中国大陆科学钻探实施15周年（2001~2016）,本文回顾中国大陆科学钻探实施15年来的艰辛和奋斗的历程,展望中国大陆科学钻探的未来。     

不同近岸河床组成情况下岸坡崩塌试验

在弯道水槽中开展6组试验,分别用非黏性土及黏性土填筑河床,研究相同水力作用下近岸河床组成对黏性岸坡崩塌的影响规律。研究发现,在试验给定的岸坡及河床组成情况下,非黏性河床凹冲凸淤且总体表现为淤积,近岸河床及凹岸岸坡冲刷强度大,凸岸附近床面上泥沙掺混较明显;黏性河床及凹岸岸坡均被冲刷,河床主流区冲刷强度比近岸河床及凹岸岸坡大。相较于黏性河床,非黏性河床近凹岸处较易冲刷,水流结构重新调整,凹岸坡脚处水流流速及紊动能可增至2倍左右,环流强度可增至11倍,加速了岸坡崩塌及崩塌体的分解输移;非黏性河床近凹岸坡脚处变形以及凹岸岸坡崩塌量均相对较大,岸坡崩塌强度为河床淤积强度的2~4倍,崩塌物质可充分补给河床的泥沙来源;经水力冲刷后非黏性河床组成情况下形成的河道滩槽高差相对较小,河道横断面相对宽浅。     

分形分维理论在地质灾害发育及空间分布规律中的应用——以长安区滑坡、崩塌地质灾害为例

长安区区内地层岩性、地质构造多样,加之人类经济工程活动、降雨、地震等诱发影响,秦岭北坡及黄土台塬边缘滑坡崩塌地质灾害发育,是陕西省地质灾害较严重的县(区)之一。本文以长安区为研究区域,在对长安区自然地理及区域地质环境条件等资料充分收集的基础上,结合长安区滑坡崩塌灾害点的实际调查资料,详细分析了长安区的滑坡崩塌灾害发育特征及空间分布规律,并采用网络覆盖法,对长安区滑坡崩塌地质灾害的空间分布进行了分形分维计算。求得地质灾害的空间分布分维值为0.876 6,反应出长安区滑坡崩塌地质灾害空间分布特性的复杂性。研究结果表明,分形分维理论能合理评价地质灾害空间分布特征,对类似地区的地质灾害空间分布特征分析具有借鉴意义。