Study on Longitudinal Deformation Profile of Rock Mass in a Subsea Tunnel

During tunnel excavation, the deformation of surrounding rock due to the unloading of rock mass will vary with time. However, the measured displacement of surrounding rock is only a part of the actual longitudinal deformation profile. There is a need to analyze the longitudinal deformation profile to identify the deformation state and evaluate the stability of surrounding rock mass. In the present article, the variation of pre-deformation of surrounding rock due to excavation was analyzed, and the release coefficient was obtained from the measured results. For the Qingdao subsea tunnel, the measured crown settlement of surrounding rock was analyzed using the regression analysis method, and the longitudinal deformation profile of rock mass was simulated using the numerical calculation method. Moreover, based on the conditions of the subsea tunnel, a solid-fluid coupling model test was carried out to check the reliability of the numerical calculation results. The results of the model test were consistent with the numerical calculation results.     

“松科二井”用硬岩长寿命钻头的设计与应用

为提高“松科二井”在深井硬岩钻进中的寿命与效率,选用了高性能胎体材料、高强度焊接材料,并采用了合理的钻头结构与水路结构设计,研制的φ216/124 mm金刚石取心钻头在“松科二井”取得了良好的效果,本文介绍了适用于深井硬岩的金刚石钻头的设计及应用效果。     

软岩隧道中双层初期支护的应力情况分析

两水隧道穿越的地层主要岩性为炭质千枚岩,地质情况较差,围岩破碎度高,节理发育。自2009年两水隧道开工建设以来,隧道工程问题层出不穷,出现了初期支护开裂、破坏,甚至出现二衬开裂、掉块,仰拱隆起等严重的隧道结构破坏现象,施工进度缓慢。在进口桩号为DK359+712～ DK359+742段采用双层初期支护和单层二次衬砌的支护方式,取得了良好的效果。通过应力情况分析为炭质千枚岩隧道的支护选型提供了依据。     

西藏加查拉岗村巨型古滑坡发育特征与形成机理研究

青藏高原地质构造活跃,内外动力作用强烈,加之气候异常变化,区内大型滑坡发育。以雅鲁藏布江断裂附近新发现的拉岗村古滑坡为研究对象,在现场调查、槽探揭露、地质测年和工程地质分析等基础上,对其发育特征及成因机制进行了分析研究。研究表明,(1)拉岗村滑坡属巨型岩质滑坡,体积达3.6×107 m3,最大水平滑动距离约3050m,滑坡后壁与堆积体前缘高差达965m,最大运动速率达78.1m/s,具明显高速远程特征;(2)受冷冻风化和冰体"楔劈"作用影响,滑坡后部岩体崩裂,全新世以来气候变化冰川逐渐消退,融雪降水入渗加剧劣化岩体结构,降低岩体强度;(3)根据14 C和10Be测年结果,拉岗村古滑坡形成于距今4140~9675a,沿雅鲁藏布江断裂发生的强震可能是该滑坡的直接诱因,岩体受到地震抛掷力作用,原有节理裂隙和新生破裂面发生张剪-拉裂破坏迅速贯通,首先沿断裂附近碎裂结构岩体发生破坏,上部岩体随之失稳并高速下滑。该研究可为认识青藏高原断裂带内大型古滑坡的形成机理提供借鉴。     

基于理想点-可拓云模型的隧道围岩稳定性评价

为了对隧道围岩稳定性进行准确评价并解决研究过程中存在的模糊性和随机性以及评价指标不相容的问题,减少单一的主客观赋权法所带来的误差,将云模型引入可拓理论中,利用可拓理论能够实现矛盾问题向相容问题转化的特点和云模型具有处理事物双重不确定性的优势并结合理想点组合赋权法对隧道围岩进行稳定性评价研究。通过文献调研、数据统计的方式,选取具有代表性的6个指标组成隧道围岩评价指标体系,用理想点法赋予评价指标组合权重,并构建可拓云模型对隧道围岩稳定性进行综合评价。通过将此方法应用于工程实例并与其他方法对比,结果表明:基于理想点-可拓云模型的隧道围岩稳定性评价方法能够减少评价过程中存在的不确定性问题,克服单一赋权方法的不足,具有良好的适用性,可以应用于实际工程中。     

热带气旋西行造成的远距离降雨特征分析

2018年7月27~28日凉山州地区出现了持续性的强降水天气过程,本文运用水平分辨率为1°×1°的NECP6小时再分析资料、新型监测资料及常规观测资料进行分析。发现此次过程不同于常规的降水过程,环流背景上受副高外围的东南气流和热带气旋形成的东风波倒槽共同作用形成的急流轴影响,为降水地提供充足的水汽和能量补充,从而形势上形成了热带气旋远距离降水,同时副热带高压的稳定维持也阻挡了高原上的低值系统快速东移,使得降水机制长时间停滞,对降水地造成影响。     

基于小波长短期记忆网络的风电功率超短期概率预测

随着大规模的风电并网,风电所具有的间歇性与随机性对电力系统的稳定性产生了很大的影响,风电功率预测成为当前解决该问题重要的方式之一.本文利用长短期记忆（LSTM）网络良好的时序记忆特性,将小波分解技术与LSTM深度网络结合,提出基于小波长短期记忆网络的风电功率超短期概率预测模型.首先通过小波分解技术将原始时间序列进行平稳化处理,再建立各子序列样本的LSTM网络预测模型,借助最大似然估计法估计预测误差的高斯分布函数,最终实现对未来4 h时刻的风电功率概率区间预测.最后,采用中国东北某风电场数据对所提方法进行算例分析,结果表明,将小波分解与深度学习方法结合可以较好地提高预测的精度,提高概率预测的区间可靠性.     

THE ‘NEW IMPLICIT METHOD’ FOR TUNNEL ANALYSIS

Tunnel excavation is a coupled three-dimensional problem dealing with two different structures: lining and rockmass. For a simple application it is useful to develop simplified methods by treating the problem as plane strain. If the problem of tunnel face advance presents an axisymmetric geometry, then we show that the major parameter governing the ground–interface–lining interaction is the convergence of the tunnel U₀ at the moment of the lining installation. The ‘New Implicit Method’ (NIM) presented in this paper makes use of principles similar to those of the ‘convergence–confinement’ method, but it provides a better appreciation of the coupled behaviour of rockmass and lining. For independent time constitutive laws (elasticity and plasticity), we point out that the convergence U₀ depends not only on the mechanical behaviour of the rockmass and on the distance from the tunnel face, as predicted by the ‘convergence–confinement’ method, but also on the stiffness of the lining previously set. We present the ‘NIM’ for elastic and perfect elastoplastic rockmasses without dilatancy for many criteria. The development of this new method is based on the results of tunnel calculations with an axisymmetric FEM numerical model that takes into account the three-dimensional aspect of the problem. Using this method is simple and its results agree well with the FEM numerical results. Its accuracy is highly satisfactory for a geotechnical study.     

坐标转换模型在盾构姿态计算中的应用

在附有条件的间接平差模型的基础上,提出用归一化大角度坐标转换模型计算盾构机姿态,并从其原理、方法以及精度上进行了分析。应用结果表明:利用坐标转换法计算盾构机姿态,与常规解方程法相比较更能有效利用参考点的所有信息,计算过程简明,且便于程序实现。     

A comparative study between China and U.S. on seismic design philosophy and practice of a long span arch bridge

This paper presents the first of a series of case studies on the seismic design of long span bridges （cable-stayed bridges, suspension bridges and arch bridges） under a cooperative research project on seismic behavior and design of highway bridges between the State Key Laboratory for Disaster Reduction in Civil Engineering, Tongji University and the Multidisciplinary Center for Earthquake Engineering Research, University at Buffalo. The objective of this series of case studies is to examine the differences and similarities on the seismic design practice of long span bridges in China and the U.S., to identify research needs and to develop design guidelines beneficial to bridge engineers in both countries. Unlike short to medium span bridges, long span bridges are not included in most seismic design specifications, mainly because they are location dependent and structurally unique. In this paper, an available model of a steel tied half through arch bridge with a main span of 550m in China is discussed. Analysis is focused on comparisons of the seismic responses due to different ground motions. Seismic design criteria and seismic performance requirements for long span bridges in both countries were first introduced and compared, and then three near field earthquake records with large vertical components were selected as the excitations to examine the seismic behavior and seismic vulnerability of the bridge. Results show that （1） the selected near field ground motions cause larger responses to key components （critical sections） of the bridge （such as arch rib ends） with a maximum increase of more than twice those caused by the site specific ground motions; （2） piers, longitudinal girders and arch crowns are more vulnerable to vertical motions, especially their axial forces; and （3） large vertical components of near field ground motions may not significantly affect the bridge＇s internal forces provided that their peak acceleration spectra ordinates only appear at periods of less than 0.2s. However, they may have more influence on the longitudinal displacements of sliding bearings due to their large displacement spectra ordinates at the fundamental period of the bridge.