The Kangding earthquake swarm of November, 2014

There was an earthquake swarm of two major events of MS6.3 and MS5.8 on the Xianshuihe fault in November, 2014. The two major earthquakes are both strike-slip events with aftershock zone along NW direction.We have analyzed the characteristics of this earthquake sequence. The b value and the h value show the significant variations in different periods before and after the MS5.8earthquake. Based on the data of historical earthquakes, we also illustrated the moderate-strong seismic activity on the Xianshuihe fault. The Kangding earthquake swarm manifests the seismic activity on Xianshuihe fault may be in the late seismic active period. The occurrence of the Kangding earthquake may be an adjustment of the strong earthquakes on the Xianshuihe fault. The Coulomb failure stress changes caused by the historical earthquakes were also given in this article. The results indicate that the earthquake swarm was encouraged by the historical earthquakes since1893, especially by the MS7.5 Kangding earthquake in1955. The Coulomb failure stress changes also shows the subsequent MS5.8 earthquake was triggered by the MS6.3earthquake.     

透岩浆流体作用与矿田构造

从透岩浆流体成矿理论的角度对矿田构造进行了重新认识,提出矿田构造系统是一种复杂性动力系统的观点。根据这个模型,矿田构造是近场应力场与远场应力场强烈相互作用的产物。近场应力场由岩浆成矿系统而不是远场应力场派生,因而不能由矿田构造反演区域构造,但可以从区域构造限定矿田构造。矿田构造常有岩脉和热液脉充填,因而是可识别的。利用构造统计学方法,可以根据岩脉和/或热液脉的分布密度图(或等值线图)预测找矿靶区。     

断裂构造控矿的数学和力学分析：以山东新城——河西金矿区为例

以山东新城－河西金矿区为例,通过新城、河西和候西矿床容矿断裂的形态、断裂活动、构造因素、构造应力场和变形场的数学、力学半定量及定量分析,探计断裂构造控矿规律以及成矿的力学机理。提出了金矿成矿受主断裂面形态、次级小断裂、节理的发育强度,断裂构造的力学特征、变形强度等控制。矿体多位于波状起伏的主断裂面凸峰的下盘、凹谷的上盘。矿化强度与次级断裂、节理的发育强度正相关。断裂构造带和次级构造裂隙带是内应力低     

岩石变形、流体压力与热液成矿关系的研究现状

地壳中岩石的变形模式受构造应力、流体压力和上覆岩层重力共同作用的影响。岩石组成和构造应力的大小、方向决定着岩石的变形过程,同时岩石的破裂还受先存断裂构造的影响。流体压力增大,岩石可以发生水力破裂,而引起水力引张破裂的条件是σ1-σ3<4T和Pf=σ3+T。随着深度的增加,受地温梯度的影响,岩石由脆性变形向韧性变形转变。在无流体超压影响的情况下,脆韧性转换的温度在300~450℃之间,大约在地壳15km处。当流体压力和应变速率增大时,韧性条件下的岩石变形行为由韧性向脆性变化,脆韧性转变的深度随之增大。从构造角度探讨热液成矿作用,热液矿床形成的深度与流体压力、应变速率、裂隙的发育、介质的渗透率、温度变化等相关。岩石断裂的类型和方向影响岩石的渗透率,提供流体运移的通道和聚集场所,控制矿床形成的深度、位置和矿体产状。     

应力分散型预应力抗拔桩系列技术研究与应用

根据目前国内外预应力抗拔抗浮桩、部分粘结预应力抗拔抗浮桩的优缺点以及使用的局限性——长螺旋钻机对于桩径＞800 mm或桩长＞30 m的桩力不从心,研究了应力分散型预应力抗拔桩及钢筋钢绞线笼系列技术,用于一个直径1 m、桩长60 m的抗拔桩工程,采用旋挖成孔,可实现在工程桩上进行大吨位试桩,受力合理,节省资金和工期,实践证明该系列技术有很好的应用前景。     

Characteristics of the Mesozoic and Cenozoic Tectonic Stress Fields of the Urumqi-Usu Region, Xinjiang

Based on the study of folds and related conjugate shear joints, the tectonic stress fields of the Urumqi-Usu region to the north of the North Tianshan Mountains have been reconstructed. Furthermore the author discussed the tectonic movements and their dynamic features. The early tectonic movement in the investigated region occurred from the end of the Late Jurassic to the initial stage of the Early Cretaceous, with the maximum (tensile) and minimum (compressional) principal stress trajectories in the tectonic stress field being in E-W and S-N directions respectively; the late tectogenesis took place from the end of the Early Pleistocene to the initial Middle Pleistocene, with the maximum and minimum principal stress trajectories in the late stress field striking in WNW and NE-NNE directions respectively. Through computer-aided simulated calculation by the finite element method and analysis of geological structure, it has been ascertained that the early tectogenesis is a nearly N-S compressive movement and the late one a NE to nearly N-S compressive movement with reverse shear. The dynamic force which caused the tectogeneses came from the movement of the southern major fault, i.e. the North Tianshan Mountains.     

应力路径对饱和软黏土割线模量的影响

在基坑、隧道开挖等过程中,不同部位的土体会经历不同的应力路径,在不同的应力路径下,土体可能表现出截然不同的静力学特性。同时,在工程实际中,土体的工作应变经常处于小应变范围,而在小应变情况下,土体的静力特性表现出更强的非线性和应力路径依赖性。基于广泛分布于东部地区,并且表现出诸多不良工程特性的软黏土,进行一系列不排水和排水条件下的应力路径静力试验,以研究应力路径对饱和软黏土静力特性,尤其是小应变情况下割线模量的影响。试验结果表明,不管在不排水还是在排水条件下,应力路径都对饱和软黏土的静强度产生巨大的影响,表现为围压增加的加载应力路径增大了静强度,而围压减小的卸载应力路径降低了静强度。同时,应力路径对割线弹性模量产生了更大的影响,围压增加的加载应力路径降低了割线模量,而围压减小的卸载应力路径增大了割线模量。应力路径对割线模量的影响在小应变时表现的更加明显,而这种影响主要原因是应力路径方向改变造成的土体各向异性。     

Hydrological characteristics of vegetated river flows: a laboratory flume study

Abstract

Laboratory flume experiments were undertaken to measure the vertical profiles of mean flow velocity for three different flow discharges and four different stem densities of Hydrilla verticillata. The data were used to calculate three parameters, namely Manning's roughness coefficient, the Reynolds number and the Froude number. In addition, empirical equations were obtained for the vertical distribution of measured flow velocity within the transitional zone and above the plant canopy. The results show that: (a) the vertical distribution of measured flow velocity exhibits three zone profiles; (b) Manning's roughness coefficient decreases with increasing depth-averaged flow velocity; (c) the relationship between Manning's roughness coefficient and the depth-averaged flow velocity is within the smooth left inverse curve; (d) Manning's roughness coefficient significantly changes with increasing density of Hydrilla; (e) the Froude number is independent of the density of Hydrilla; and (f) both the Reynolds number and the Froude number increase with increasing depth-averaged flow velocity.

Citation Shi, J.Z., Li, Y.-H., Hughes, J.M.R., and Zhao, M., 2013. Hydrological characteristics of vegetated river flows: a laboratory flume study. Hydrological Sciences Journal, 58 (5), 1047–1058.

Editor Z.W. Kundzewicz     

Examining human heat stress with remote sensing technology

Heat stress as an environmental hazard which can seriously affect productivity, health, or even survival of individuals has long been studied. Despite the endeavors that have been made to address the issue quantitatively with various heat stress indices, they are often measured at scatter sites. This research devotes to revealing human heat stress within continuous space with remote sensing technology. The study began with the retrieval of dry-bulb temperature from land surface temperature (LST) with empirical models. As wet-bulb temperature was calculated from dry-bulb temperature and relative humidity, discomfort index (DI) as an indicator of heat stress was revealed for the study area at 1 km spatial resolution for three summer days. Results indicated that DI can be derived within continuous space with remotely sensed data, and its spatial distribution can be dramatically affected by relative humidity. Further comparison between DI and LST indicated that LST as a widely utilized indicator of surface thermal condition fails to address human heat stress as environmental factors such as relative humidity are not taken into account.     

An Empirical Tropical Instability Wave-induced Wind Stress Model in the Equatorial Pacific and its Incorporation into the Ocean Model

Abstract

Satellite observations revealed that there is a close relationship between perturbations of sea surface temperature (SST) and wind stress (τ) induced by tropical instability waves (TIWs; SST_TIW and τ _TIW). Using the empirical relationship observed between TIW-induced wind stress divergence (curl) and downwind (crosswind) SST gradients, this study establishes a TIW-induced wind stress field perturbation model τ _TIW?=?F(SST). This empirical model solves τ _TIW from the TIW-induced wind stress divergence and curl, which are estimated from the downwind and crosswind SST gradients. This empirical τ _TIW?=?F(SST) model can be incorporated into the ocean model to take into account the effect of τ _TIW. By comparing two experiments with and without the τ _TIW effect, this study demonstrates that τ _TIW has a substantial effect on the equatorial Pacific heat budget and induces the long-term mean SST to exhibit a 0.2°C difference, which is consistent with previous studies.