析岩土工程勘察中存在的问题

岩土工程勘察是工程建筑中的一个重要步骤，要保证工程按时、保质、保量完成.岩土工程勘察工作的准确性和全面性十分重要。但据笔者的经验.工程建设中。投资方（下简称甲方）往往由于对岩土工程勘察的专业性不了解.在与勘察方（下简称乙方）的沟通中存在认识上的差别．使岩土工程勘察出现了一些不符合技术要求的问题。现就岩土工程勘察中的3个主要问题分析如下。     

四川雅砻江某大型崩塌堆积体滑坡勘察及治理思路

四川雅砻江某堆积体分布面积广,体积巨大,仅本次研究的前缘变形部分体积就达3 500万m3以上。堆积物成分主要为灰岩块石、碎石夹黏土,局部为大孤石组成。本文从勘察技术、成因、边界条件、综合治理等方面着手,对该工程实例加以介绍,供同行参考。     

岩土工程勘察中的注意事项

近年来工程勘察技术手段发展迅速,研究领域不断拓展,向着岩土工程勘察设计一体化方向发展;在发展的过程中还存在不少问题,特别是工程勘察与设计施工的配合及工程勘察内部各工序间衔接都有很多值得商榷和优化之处。作者对岩土工程勘察中存在的问题和改进的措施提出了见解。     

岩土勘察工程中常见的问题及解决措施

在工程施工中,有一个很重要的环节就是岩土勘察.岩土勘察主要就是对所施工的场地岩土体进行勘查.因为勘察报告是建筑结构设计的最重要的依据.所以岩土勘察报告的质量好坏会直接影响到整个工程的质量好坏.工程建设的设计和施工前务必要按照程序进行岩土工程勘察.文章对岩土勘察中存在的问题和解决的措施等方面进行阐述.     

汶川县雁洛大型堆积体特征及成因

基于详细的野外调查,对汶川县雁门乡雁洛村发育的大型堆积体的基本特征、形成及演化过程进行较深入研究,结果表明:雁洛堆积体为残坡积、崩坡积、类黄土堆积以及滑坡堆积等4部分组成的复合堆积,平面上可分2个大区、6个次级区;结合侧缘基岩变形迹象以及UDEC数值模拟对滑坡的形成机制进行分析,其变形破坏模式为弯曲-拉裂模式;雁洛堆积体演化经历早更新世宽谷期黄土堆积阶段,中、晚更新世峡谷期谷坡卸荷变形阶段,峡谷区滑坡形成阶段,全新世堆积体复活变形阶段等4个阶段。     

淮北地区填土的岩土工程勘察及评价

填土是指由人类活动在地表形成和任意堆积的土层,它的组成成份复杂,堆填的方法、时间和厚度都是随意的。安徽省淮北地区由于有相同的地理、地貌、地质环境和共同的经济和社会发展的历史背景,各地填土具有相似的物理力学性质等特点。近年来随着改革开放和经济建设发展,城市房地产开发、道路、水利等固定资产投入的加大,对填土的工程勘察和评价提出越来越高的技术要求。下面谈谈如何开展填土工程地质勘察及评价。1 概述 填土主要分布在老城区和工矿附近以及河道旁。按照其物质组成和堆填方式可以分为素填土、杂填土和冲填土。素填土是由天然土经人类扰动难填而成,不含或只含少量杂质,素填土不具天然土的结构和层理。淮北地区素填土分布数量     

影响水利水电工程勘察质量的主要原因分析与思考

简要分析水利水电工程勘察质量现状；指出影响水利水电工程勘察质量的主要原因，包括勘察市场不规范，勘察设计周期短，工程勘察取费低，队伍建设落后，管理机制问题突出等几个方面；建议采取以下措施，即各级领导重视，加大制度的建设和落实，规范市场秩序，提高勘察队伍职工的整体素质，加强与设计部门的沟通配合，积极椎广应用新技术等。以提高水利水电工程勘察质量。     

岩土工程勘察过程中应注意的问题

岩土工程勘察在整个过程建设中起着重要的作用,勘察结果不但是工程项目规划、设计、施工的基础,同时勘察质量的好坏直接影响到后期工程的质量以及安全。只有保证岩土工程勘察的质量,才能使得整个工程建设更加有保障。本文分析了在进行岩土工程勘察的时候应注意的一些问题,旨在能够为相关的同行进行岩土工程勘察起到一定的借鉴意义。     

西藏某水电站近坝库岸滑坡稳定性分析与评价

近坝库岸堆积体边坡的稳定性,对电站的安全运行及其上居民安全影响至关重要。以西藏某水电站近坝库岸滑坡堆积体为例,针对该滑坡堆积体蠕变、蠕滑进行了专门的勘察与监测,通过勘探、物探、试验及变形监测等资料,采用极限平衡法及有限元强度折减法进行稳定性分析,查明了堆积体的稳定边界条件,验证了滑坡堆积体的变形破坏形式与实际相吻合。结果表明:堆积体整体处于临界失稳状态,预测其破坏形式将以蠕滑塌岸的方式调整至稳定,不会产生大范围的高速滑坡,同时也不会堵塞水库。     

三维立体成图技术——在工程物探勘察中的应用

工程物探勘察是工程勘察的重要组成部分。工程勘察中的点、线资料无法直观的体现工程勘察部位各个位置的相对信息,因此集合工程勘察中的多点、多线信息,组合成工程物探勘察三维数据库,可实现直观反映工程勘察部位的三维立体信息,如:地面等高度图;水域等深度图;覆盖层等深度图;地层的等厚度图及基岩面等高度图。     

三种土壤质地工程堆积体坡面流速及产沙特征

生产建设项目工程堆积体由于土壤质地、砾石质量分数差异较大,导致侵蚀过程流速及产沙特性发生变化。通过人工模拟降雨试验,研究砂土、壤土及黏土3种土壤质地堆积体的流速与产沙特性。结果表明:①堆积体坡面流速在产流开始3 min内递增,随后趋于稳定;②小雨强时砂土堆积体侵蚀主要发生在产流的中后期,壤土堆积体发生在产流前期和中期,而黏土堆积体的侵蚀发生在整个降雨过程,21 min后的累计产沙量占次降雨总产沙量砂土、壤土和黏土堆积体分别为52.3%~95.6%、29.6%~44.9%和42.1%~50.0%;③产流历时、雨强与径流率、入渗率、流速、产沙率均呈显著相关性;④雨强增加1.5~2.0倍,3种土质堆积体侵蚀量增大1.2~39.8倍。相同雨强下砂土堆积体侵蚀量是壤土的6.0~6.3倍,是黏土的3.2~3.5倍;相同砾石质量分数下砂土堆积体侵蚀量分别是壤土和黏土的5.0~9.8倍和2.7~3.8倍。研究成果对于明确含砾石堆积体侵蚀过程机理具有重要意义,并为建立堆积体侵蚀预报模型奠定基础。     

Transient organic jams in Puerto Rican mountain streams after hurricanes

Extreme storms in forested environments commonly increase inputs of coarse particulate organic matter (CPOM) and large wood (LW) to streams. Protruding boulders and bedforms, mid‐channel bars, and standing trees can trap CPOM and LW. These organic accumulations can become large enough to span the bankfull channel width, or the accumulations can be predominantly along the channel margins. We refer to both types of accumulations as transient organic jams (TOJs). TOJs can create diverse geomorphic and ecological effects in channel and floodplain environments. We use data collected from mountain streams of the Luquillo Mountains of north‐eastern Puerto Rico following September 2017 Hurricanes Irma and Maria. We examine the location, characteristics, and geomorphic effects of TOJs in channel segments representing diverse drainage areas and channel gradients. We ask three questions: (a) Does the downstream spacing of TOJs correlate with variables such as drainage area or channel gradient? (b) What variables best predict the volume of organic matter within individual TOJs or within a channel segment? And (c) is there a threshold within a river network that separates channel segments with channel‐spanning versus marginal TOJs? Datasets include multiple TOJs along each of 12 stream segments and presence/absence of channel‐spanning TOJs along an additional six streams. Data analysis with multiple linear regressions indicates that downstream spacing, average volume, and total volume per channel length of TOJs correlate significantly with bankfull channel width. Using the akaike information criterion with correction (AICc) model selection method, Strahler stream order has the most influence on the probability of TOJs being marginal or spanning.     

Great Lakes Ice Thickness Prediction

Weekly ice thickness data, collected from 24 bay, harbor, and river sites on the Great Lakes, were correlated with freezing degree-day accumulations to develop regression equations between ice thickness and freezing degree-days. The data base at ice measurement sites was 3 to 8 winters in length. Ths standard error of estimate varied for individual regression equations and averaged between 7 and 8 cm for five forms of regression equations. Because the regression equations are empirical, the range of input data used to predict ice thickness should be limited to the range of values used in the derivation.     

应该尽快促成水力发电厂独立核算

科学地核算水力发电厂提供的积累是实现水电项目滚动开发的必要条件。本文通过剖析英国电力体制改革中如何建立电力商品市场，如何实现发电商在独立核算的条件下竞争上网，如何改革电价体制，如何建立结算制度入手，表明水力发电厂实行独立核算的，并在此基础上对某些观点提出见解。     

水生生物水质基准研究进展及建立我国氨氮水质基准的探讨

水质基准是制定水质标准限值的重要依据,是科学的水质管理体系的重要组成部分。通过对国内外水生生物水质基准制定方法进行概述,综合分析了评价因子法、毒性百分数排序法、物种敏感度分布法的特点,在此基础上对基准制定方法的发展趋势进行判断。结合国外研究进展和我国实际情况,对我国氨氮水质基准的建立进行探讨,提出在不同毒性数据积累的情况下应当结合方法学特点,采用不同的方法以相对保守的方式制定我国的氨氮水质基准。     

Notable decomposition products of senescing Lake Michigan Cladophora glomerata

Massive accumulations of Cladophora, a ubiquitous, filamentous green alga, have been increasingly reported along Great Lakes shorelines, negatively affecting beach aesthetics, recreational activities, public health and beachfront property values. Previously, the decomposition byproducts of decaying algae have not been thoroughly examined. To better understand the negative consequences and potential merit of the stranded Cladophora, a three month mesocosm study of the dynamic chemical environment of the alga was conducted using fresh samples collected from southern Lake Michigan beaches. Typical fermentation products, such as organic acids, sulfide compounds, and alcohols were detected in the oxygen–deprived algae. Short chain carboxylic acids peaked on day seven, in correspondence with the lowest pH value. Most low molecular mass carbon compounds were eventually consumed, but 4-methylphenol, indole, and 3-methylindole were detected throughout the incubation period. Natural oils were detected in fresh and decomposing algae, indicating the stable nature of these compounds. The mesocosm experiment was validated by directly sampling the fluid within decomposing Cladophora mats in the field; many of the same compounds were found. This study suggests that the problematic Cladophora accumulations may be harvested for useful byproducts, thereby reducing the odiferous and potentially harmful mats stranded along the shorelines.     

河冰水力学研究进展

北方地区的河流冬季会形成冰盖，继而可能导致冰冻期或开河期的冰塞，冰塞是最严重的河冰问题之一，冰盖和冰塞的堆积导致水流阻力增加，使上游水位上涨并可产生凌洪，也会形成冰期的河床演变．由于问题的重要性，国内外相关领域的专家都很关注，对目前国内外河冰水力学研究的现状进行了综述和分析，内容主要涉及原型观测、试验研究和数学模型及计算机模拟等方面，提出了今后研究的方向。     

粗、巨颗粒富集位置对堆积体降雨入渗的影响

针对某堆积体局部粗、巨颗粒于坡中、坡脚不同发育位置富集现象展开室内降雨模型试验,通过孔隙水压力、基质吸力、体积含水率及湿润锋迁移形态的变化情况,探讨粗、巨颗粒于堆积体坡中、坡脚位置局部富集在降雨入渗过程中的差异性影响。研究表明:（1）坡中（A组）、坡脚（B组）局部粗、巨颗粒富集导致的架空现象致使降雨过程中形成雨水优势入渗通道,富集区下方的入渗速率明显快于周围均质土体;（2）B组堆积体右侧入渗速率比A组堆积体更快,而左侧入渗速率不及A组堆积体;（3）B组堆积体的整体渗流特性更强,其湿润锋运移率先触底,比A组堆积体提前72 h;（4）A组堆积体湿润锋迁移形态先期中部呈平缓凹形下渗,较B组右侧凹形下渗范围更宽;后期均呈平滑弧形入渗,而B组堆积体浸润面积较A组更小。（5）A、B组堆积体降雨入渗可划分为竖向入渗阶段和侧向入渗阶段,但存在明显差异,A组堆积体竖向入渗快于侧渗,而B组堆积体竖向入渗慢于侧渗。     

Sediment Distribution and Bottom Topography of Southeastern Lake Superior

Sediment distribution in the complex region of troughs and shoals in southeastern Lake Superior was studied by means of echo sounding, coring and surface sediment sampling. The primary factor governing sediment type is water depth with sediment source, water movement, trough morphology and lake history superimposed upon it.Thick accumulations of fine-grained sediment are confined to the trough bottoms whereas coarser sediments occur on the sides and crests. In the southern part of the region subaqueous erosion of red tills leads to the deposition of brown sandy sediments whereas farther offshore dark gray fine-grained sediments show the influence of eroding varved clays. Current action along the south shore and along the trough bottoms produces sediment sorting even in deep water. On slopes greater than one op two degrees, fine-grained postglacial sediment is very thin or absent and lag deposits overlie glacial sediments. Evidence of ice scour indicates that modifications to sediment distribution may have occurred during the low level Houghton stage about 8000 B.P.Stratigraphic evidence suggests that the most probable origin of the complex bottom topography is erosion by moving ice.