Results of the Study of Zircon (SIMS) from Granitoids of the Konstantinovskii Stock (Area of the Sukhoi Log Gold Deposit): Age,Sources, and Geological Consequences

Doklady Earth Sciences - The results of U–Pb geochronological (SIMS) study of zircons from granitoids of the Konstantinovskii Stock located 6 km from the Sukhoi Log gold deposit are reported....     

The Strong Earthquake in Sakhalin Island in September 13, 2020

Doklady Earth Sciences - The seismotectonic position of the strong earthquake that occurred in the southern part of Sakhalin Island on September 13, 2020, is considered. The maximum shaking...     

Field study on the behavior of pre-bored grouted planted pile with enlarged grout base

This paper presents the results of field tests performed to investigate the compressive bearing capacity of pre-bored grouted planted (PGP) pile with enlarged grout base focusing on its base bearing capacity. The bi-directional O-cell load test was conducted to evaluate the behavior of full scale PGP piles. The test results show that the pile head displacements needed to fully mobilize the shaft resistance were 5.9% and 6.4% D (D is pile diameter), respectively, of two test piles, owing to the large elastic shortening of pile shaft. Furthermore, the results demonstrated that the PHC nodular pile base and grout body at the enlarged base could act as a unit in the loading process, and the enlarged grout base could effectively promote the base bearing capacity of PGP pile through increasing the base area. The normalized base resistances (unit base resistance/average cone base resistance) of two test piles were 0.17 and 0.19, respectively, when the base displacement reached 5% D_b (D_b is pile base diameter). The permeation of grout into the silty sand layer under pile base increased the elastic modulus of silty sand, which could help to decrease pile head displacement under working load.

     

Basal stability analysis of braced excavations in anisotropic and non-homogeneous undrained clay using streamline velocity fields

Acta Geotechnica - A basal heave stability analysis in anisotropic and non-homogeneous undrained clay by using the kinematic approach of limit analysis is presented. The proposed failure mechanism...     

Landslide susceptibility zonation method based on C5.0 decision tree and K-means cluster algorithms to improve the efficiency of risk management

Machine learning algorithms are an important measure with which to perform landslide susceptibility assessments,but most studies use GIS-based classification methods to conduct susceptibility zonation.This study presents a machine learning approach based on the C5.0 decision tree(DT)model and the K-means cluster algorithm to produce a regional landslide susceptibility map.Yanchang County,a typical landslide-prone area located in northwestern China,was taken as the area of interest to introduce the proposed application procedure.A landslide inventory containing 82 landslides was prepared and subse-quently randomly partitioned into two subsets:training data(70％landslide pixels)and validation data(30％landslide pixels).Fourteen landslide influencing factors were considered in the input dataset and were used to calculate the landslide occurrence probability based on the C5.0 decision tree model.Susceptibility zonation was implemented according to the cut-off values calculated by the K-means clus-ter algorithm.The validation results of the model performance analysis showed that the AUC(area under the receiver operating characteristic(ROC)curve)of the proposed model was the highest,reaching 0.88,compared with traditional models(support vector machine(SVM)=0.85,Bayesian network(BN)=0.81,frequency ratio(FR)=0.75,weight of evidence(WOE)=0.76).The landslide frequency ratio and fre-quency density of the high susceptibility zones were 6.76/km2 and 0.88/km2,respectively,which were much higher than those of the low susceptibility zones.The top 20％interval of landslide occurrence probability contained 89％of the historical landslides but only accounted for 10.3％of the total area.Our results indicate that the distribution of high susceptibility zones was more focused without contain-ing more"stable"pixels.Therefore,the obtained susceptibility map is suitable for application to landslide risk management practices.     

Liquid bridge contribution to shear behavior of unsaturated soil: modeling and application to a micromechanics model

Acta Geotechnica - Liquid bridges in unsaturated soils attach to grain contacts and contribute to strengthening microscopic bonding forces, which leads to macroscopic high strength and stiffness...     

国内外CO2地质封存潜力评价方法研究现状

碳捕集与封存(Carbon Capture and Storage,CCS)技术作为缓解全球气候变暖、减少CO₂排放的有效路径之一,其潜力评估至关重要。目前CCS技术主要包括CO₂强化石油(天然气)开采封存技术、CO₂驱替煤层气封存技术以及咸水层CO₂封存技术3类。各类封存技术利用了不同的封存机制,其潜力评估方法也略有差别。油气藏封存和咸水层封存主要利用了构造圈闭储存、束缚空间储存、溶解储存、矿化储存等封存机制,煤层气封存主要利用了吸附封存机制。国内外学者和机构针对各类封存技术提出了相应的计算方法,依据其计算原理可归纳为4类: 物质平衡封存量计算法、有效容积封存量计算法、溶解机制封存量计算法以及考虑多种捕获机制的综合封存量计算法。通过对各类经典方法及其计算原理进行综述,剖析潜力封存量计算方法的内涵原理和应用场景,分析了CO₂地质封存潜力评价方法在实际应用中面临的问题,有助于提升我国的CCS潜力评价质量。     

市级自然资源调查监测体系构建探索——以徐州市为例

自然资源调查是实现自然资源统一管理的重要前提和基础性工作。本文通过对自然资源分类体系、调查方案和数据库组织的研究,构建了以第三次国土调查和各类专项调查数据为基础的自然资源调查监测体系,提出了新的数据库组织和更新方法,并在江苏省徐州市进行了实践验证,形成了地市级调查成果,旨在为全国范围内地级市自然资源调查工作提供参考,构建可复制、可推广的调查体系。     

碳市场顶层设计路线图

中国正面临着低碳减排和保持经济增速的双重挑战。为利用碳排放权交易机制以最低的社会成本实现减排目标,我国自2013年起开始建设碳排放权交易试点,并于2017年12月起宣布正式启动全国碳市场。然而碳市场的顶层设计不可一蹴而就,需要在我国宏观经济改革的大背景下分阶段逐步推进。短期（2020年前）碳市场建设重在强化产权制度建设,完善市场交易基础。中期（2021—2030年）碳市场建设要形成活跃的市场氛围,充分降低我国的温室气体达峰成本。长期（2031—2050年）碳市场建设要形成稳定上升的碳价趋势,为我国的低碳转型提供长期动力。     

淮河流域(河南段)连续性暴雨天气分型及环流背景

利用19812016年68月河南省淮河流域64个国家自动观测站逐日2020时日降水量资料、常规高空探测和地面观测资料等对淮河流域连续性暴雨时间分布特征、影响系统等进行分析和天气分型,结果表明:1)36年淮河流域共发生45次连续性暴雨,2000年的最多,19982008年是高发期,近10年较少,年出现次数无明显减少趋势,存在2~4年和4~6年两个周期;7月连续性暴雨次数最多,6月的最少,旬分布呈正态分布;最长连续时间5天,连续2天的最多。2)影响系统主要有切变线和高低空急流,高空急流在方向转换的过程中,降水有24h左右的减弱期,低空急流有明显的日变化特征,夜间加强,白天减弱。3)连续性暴雨按照500hPa影响系统,分为低槽型、副高边缘型、西北低涡型三类。4)以不同类型的3次典型连续性暴雨为例,从大尺度环流背景、高度距平场、水汽输送、高低空急流等方面探讨了连续性暴雨的维持成因,3次连续性暴雨的发生与异常的500hPa大气环流、高低空急流、切变线和持续偏强的水汽输送等有关。