圆曲线斜巷腰线标定方法探讨

根据伪倾角法标设腰线的原理，推导出圆曲线斜巷腰线标定的伪倾角计算公式。     

公路路基支挡结构物加固技术研究

近年来,国内各地相继出现了公路路基支挡结构物失稳事件,对相关路桥的运营安全造成了严重威胁。由于条件特殊及环境制约,此类工程加固难度很大。结合山东省G104界河立交桥加筋土挡土墙和G205高峪铺公铁立交桥坡间挡土墙的加固,对此类工程失稳的特征、原因及相应的工程对策从理论到实践展开了深入研究,并得到了具有一定推广价值的结论。     

矿山边坡加固中的稳定性综合分析

边坡加固稳定性分析是加固工程成功和经济合理性的关键性前提工作。本文提出了边坡加固的稳定性综合分析方法,并编制了稳定性综合分析程序。结合一个边坡加固工程,采用稳定性综合分析方法,计算边坡加固设计余推力,并进行适当的稳定性校核,为加固工程提供了切实可靠的边坡稳定性、加固力及加固效果的数据。加固工程已取得了良好的效果,表明稳定性综合分析方法是有效合理的。     

天山北坡短时强降水时空分布及环流配置特征

利用常规探测、自动站逐时雨量及ECMWF0.25°×0.25°每日4次的ERA-interim再分析等资料,分析2010—2018年6—8月天山北坡短时强降水时空分布及其环流配置特征。结果表明:天山北坡短时强降水时空分布不均,主要发生在沿山海拔1000～2000 m区域,尤其昌吉州频次最多;雨强R≥10 mm/h出现频次2015年最多,而R≥20 mm/h出现频次相较前者骤减,2016年出现最多,均在2014年最少,且6月出现最多;短时强降水日变化明显,16时—次日03时发生频次最多,占总次数的73.8%。天山北坡短时强降水过程以局地分散性居多,占总过程的65.1%;影响系统主要分为西西伯利亚低槽(涡)、中亚低槽、中亚低涡、西北气流等4类,其中,西西伯利亚低槽(涡)、中亚低槽两者占总过程的73.2%。     

用钻孔注浆法加固涌砂坍塌地基

基坑开挖后，造成地下砂层向坑内大量涌砂，致使周围建筑基础地基塌陷，用钻孔注浆法加固砂层、填砾埋管注浆法充填加固塌陷地基是一种行之有效的方法。     

山区边坡工程监测的探讨

以某煤矿边坡监测为例,较为详细地论述了在边坡监测中的布网方案、观测方法以及监测结果分析等问题。在位移观测时采用了改进的视准线法,并对该方法的精度进行了分析,结果证明其精度可以满足二等变形观测的要求。     

Sequence architecture and depositional evolution of the Late Miocene to quaternary northeastern shelf margin of the South China Sea

Based on an integrated analysis of seismic, well logging and paleontological data, the sequence architecture and depositional evolution of the northeastern shelf margin of the South China Sea since Late Miocene are documented. The slope deposits of the Late Miocene to Quaternary can be divided into two composite sequences (CS1 and CS2) bounded by regional unconformities with time spans of 3–7 Ma, and eight sequences defined by local unconformities or discontinuities with time spans of 0.8–2.3 Ma. Unconformities within CS1 feature shelf-edge channel erosion, while in CS2 they form truncations at the top of the shelf margin as prograding complexes and onlap contacts against the slope.Depositional systems recognized in the slope section include unidirectionally migrating slope channels, slope fans or aprons, shelf-edge deltas and large-scale slope clinoforms. CS1 (Late Miocene to Pliocene) is characterized by development of a series of shelf-margin channels and associated slope fan aprons. The shelf-margin channels, oriented mostly NW-SE, migrate unidirectionally northeastwards and intensively eroded almost the entire shelf-slope zone. Two types of channels have been identified: (1) broad, shallow and unconfined or partly confined outer-shelf to shelf-break channels; and (2) deeply incised and confined unidirectionally migrating slope channels. They might be formed by gravity flow erosion as bypassing channels and filled mostly with along-slope current deposits. Along the base of the shelf slope, a series of small-scale slope fans or fan aprons are identified, including three depositional paleo-geomorphological elements: (1) broad or U-shaped, unconfined erosional-depositional channels; (2) frontal splays-lobes; and (3) non-channelized sheets. CS2 (Quaternary) consists mainly of a set of high-angle clinoforms, shelf-margin deltas and lower slope unidirectionally migrating channels.The relative sea level changes reflected in the sequence architecture of the study area are basically consistent with Haq's global sea level curve, but the development of regional unconformities were apparently enhanced by tectonic uplift. The development of high-angle (thick) clinoforms in the Quaternary may be attributed to a high sediment supply rate and rapid tectonic subsidence. The formation of the unidirectionally migrating channels appears to have resulted from the combined effects of the northeastward South China Sea Warm Current (SCSWC) and downslope gravity flow. The formation of the slope channels in the outer-shelf to shelf-break zone may be predominately controlled by bottom current, whereas those developed along the middle to lower slope zone may be dominated by gravity flow.     

Progress Review and Perspective Problems on Loess Foundation Reinforcement by Means of Modification Treatment

Based on the loess foundation modification mechanism, the methods and progress of loess foundation modification treatment application research in engineering were analyzed. The main points of the research on static and dynamic mechanical properties of modified loess were discussed. Meanwhile, the advantages and disadvantages of different modification methods were compared. Finally, the research direction of loess foundation modification in future was pointed out. The results show that there are different mechanisms between physical and chemical modifications in loess foundation. At present, researches on loess modification pay more attention to the strength and stability of the foundation under static load, which is lacking in the consideration of dynamic behaviors of loess foundation and environment factors. Research results are greatly biased, and the systematic, quantitative properties as well as standardization are weak. There is no doubt that some research directions should be concerned in future such as the research of new environmentally friendly materials and modified loess soil strength, stability of modified loess and dynamic behaviors, quantitative effect of environmental factors on the modified foundation, optimization of construction technology and fine control of construction process in the process of loess foundation modification.     

Reducing monopile rotation under lateral loading in sandy soils

Many structures (including transmission-line towers, bridges, tall buildings and coastal structures) are founded on piles, which are designed to transmit both vertical and horizontal forces, and resulting moments, to the load bearing strata. The design of such foundations for large lateral repeating loads (e.g. caused by wind, wave action, earthquake) and lateral earth pressures is a challenging task. This paper presents an experimental study that investigates the use of concentric rings (CRs) of small diameter (displacement) piles (SDPs) surrounding a monopile installed in dry sand, with the intention of limiting its rotation (lateral displacement) under repeated lateral loading. The test results showed that the rotation of the monopile, investigated for a range of different repeated lateral loading schemes, was reduced by 35?75% on account of the densification of the sand achieved during installation of the SDPs and also the lateral confinement they provided to the sand located within the CRs. Significant increases to both the cyclic stiffness and load carrying resistance of the monopile under lateral loading are documented with the inclusion of the SDPs. Further experimental as well as numerical studies are necessary to validate this novel technique and to optimise the geometrical size and network pattern of the SDPs and the CRs.     

受空洞坍塌影响的加筋路基研究综述

工程上常利用水平加筋法来预防或延迟因受交通荷载和地下水等因素导致空洞坍塌而引起的临近道路的突发性破坏,起到破坏预警作用;但加筋体界面特性与作用机制相当复杂,下伏空洞加筋路基缺少完善的设计方法。通过总结国内外已有文献的研究成果,重点阐述了受空洞坍塌影响的加筋路基-路堤力学机制与作用机制,包括对路堤填土滑移面的定义、层间土拱效应、加筋体拉膜效应、塌陷区上覆填土膨胀、锚固区筋土界面摩擦及过渡区加筋体张拉力折减等方面;总结了空洞区加筋路基已有的设计方法,并进行了对比与讨论。结果表明,已有成果对受空洞坍塌影响的加筋路基-路堤荷载传递机制、渐进性破坏演变机制、沉降计算、极限承载力与稳定性问题等方面的研究仍显不足,针对加筋体上方荷载分布形式仍未形成定论,现有设计方法过于保守,并指明了进一步的研究建议,可为今后研究提供方向和参考。