深基坑岩土工程勘察成果报告和质量信息反馈.docx

深基坑岩土工程勘察成果报告和质量信息反馈
一、深基坑勘察问题的提出、分析与处理意见
One, deep foundation pit survey questions, analysis and treatment
　　本文就软土深基坑勘察带来的一些普遍性问题展开讨论，并剖析部分案例，介绍如下。
Some common problems in deep foundation pit in soft soil survey and discuss the part of the case, and analysis, are as follows.
　　(1)对淤泥质超软弱土没做不固结不排水(UU)强度试验。
( 1 ) in the silty super soft soil didn't do the undrained strength test ( UU ).
　　众所周知，粉砂土富水性较强，而淤泥质土层富水性贫乏，在这种一侧富水，而另一侧隔水的条件下，导致在接触带上富水最集中，由于长期受其水的浸泡软化，致使淤泥质土中天然含水量很高，天然孔隙比和液性指数很大，其性质接近于淤泥，可能为淤泥质超软弱土。对这种特殊性土应进行钻探取样做不固结不排水(UU)强度试验或现场做十字板剪切试验。鉴于该土性对基坑工程的严重危害性，因此，建议钻探取样做不固结不排水(UU)强度试验或现场做十字板剪切试验，确定土的性质，同时，提醒勘察同行在进行深基坑围护方案设计时，应注意在淤泥质软土与粉砂接触带上，往往淤泥质软土是最软弱的。
As everyone knows, silty soil water is strong, and silt soil water shortage, water rich in this side, while the other side water conditions, resulting in the contact zone of the rich water, due to its water softening, resulting in the muddy soil natural water content is very high, natural void ratio and liquidity index, its nature is close to silt, silty soil is super soft. The particularity of soil should be drilling sampling do undrained ( UU) strength test or field vane shear test. In view of serious harm to the soil of the foundation pit engineering, therefore, suggest that drilling sampling do undrained ( UU ) strength test and field vane shear test, determination of soil properties, at the same time, to remind the survey and counterparts in the design of deep excavation retaining scheme, should pay attention to in silty and fine sand contact zone, often muddy soft soil is the most weak.
　　(2)没有合理分层
( 2 ) is not a reasonable stratification
　　如某超高层建筑为2F基坑，发生过深基坑整体塌滑事故，后据补勘查证，淤泥质土层很厚，达30m，按其性质可细分为3个亚层:第1层淤泥质土性质最差，含有较多的腐烂植物残骸或富含有机质，埋藏较浅，厚度较大，处于基坑开挖深度范围以内;第2层淤泥质土性质稍好，但仍处于流塑状态，厚度较大，位于坑底;第3层淤泥质土性质相对较好，其性质接近于软塑状态，但埋藏较深，形成了淤泥质土的性质由上而下逐渐变好的特征。但查看原先地质报告，发现没有对淤泥质土的明显特征引起重视，仅粗分为一个大层，由于没有细分层，导致淤泥质土统计的抗剪强度C、值偏高，是引发深基坑滑塌事故的一个重要因素之一。由此可见，对深基坑而言，细分层很重要，而对很厚的淤泥质土层更应该进行仔细分层。就本工程补勘来说，对很厚的淤泥质土层划分为3个亚层是合理的。
As a super high-rise building foundation pit for 2F, had a deep foundation pit collapse accident after overall, according to the survey to verify, mucky soil layer is very thick, up to 30m, by their nature can be divided into 3 sublayers: first layers of silt soil properties is the worst, contains a lot of decaying plant debris or rich in organic matter, buried a shallow, thick, in the excavation depth range second layers of silt soil properties is slightly better, but still in the plastic flow state, large thickness, at bottom; third layers of silt soil properties is relatively good, its nature is close to a soft plastic state, but buried deep, formed the characteristic properties of silt soil instead of getting better. But check the original geological report, found no obvious characteristics of the silty soil of the attention, only divided into a layer, because there is no subdivision of layer, resulting in shear strength C, value high silt soil statistics, is one of the important factors causing deep foundation pit collapse accident. Therefore, the deep foundation pit, subdivision layer is very important, and the silt soil is very thick should carefully layered. The engineering exploration, the silt soil classification is very thick into 3 sub layer is reasonable.
　　(3)钻探没有详细查明淤泥质土等软弱夹层
( 3 ) found no detailed drilling mud interlayer
　　如某多层住宅小区，1F地下室，但在打桩和基坑开挖过程中发现淤泥质土等软弱夹层多处没有查明，与勘察成果报告不吻合，造成多次补勘和采用加桩进行补强的措施。究其原因主要有:①地质条件复杂，据邻近场地钻探揭露，以淤泥质土为主的软弱夹层较多;②项目没有搜集资料;③对地下室勘察没有引起重视;④采用网格状布孔，由于孔少控制不了淤泥质土等软弱夹层在水平和竖向上的分布情况。应沿建筑物周边线并兼顾角点和沿基坑外侧布置勘探孔，孔距取较小值;不能打浅孔，而是深孔;不应是控制1\/5取原状土试样孔，而至少是1\/3取原状土试样孔;补勘不能都集中在所谓问题最多的地段，而还要兼顾面上的情况，分层对软弱夹层。当厚度大于0.5m的淤泥质土等软弱夹层或透镜体，宜进行单独分层。
As a multi-storey residential, 1F basement, but in the process of piling and foundation pit excavation found in muddy soil, soft interlayer multiple not identified, is not consistent with the investigation result report caused many exploration and the pile reinforcement measures. The main reasons are as follows: the complex geological conditions, according to the adjacent site drilling revealed mainly silty soil, soft interlayer more; project did not collect data; the survey did not pay attention to the basement; the grid hole, because the distribution of pores less couldn't control the mucky soil, soft interlayer on the level and the vertical. Should be around the building line and both corners and along the foundation pit lateral arrangement of exploration hole, hole spacing smaller values; can't play shallow hole, but deep; should not be controlled 1\/5 from undisturbed soil sample hole, which is at least 1\/3 from undisturbed soil sample hole; exploration can not focus on the so-called most problem areas, but also consider the surface condition, stratification of weak interlayer. When the thickness is more than 0.5m of the silty soil, soft interlayer or lens, suitable for single hierarchical.
　　(4)土工试验测试数据不正确
( 4 ) the data of geotechnical test is not correct
　　如某超高层建筑为2F基坑，从土工试验测试数据来看，淤泥质土天然含水量高达50.8﹪，天然孔隙比和液性指数接近于淤泥，对比区域水质资料，明显高出很多。分析原因:①可能受原基坑中的原河流长期浸泡软化有关;②可能与取土和土工试验操作不当有关鉴于目前取样和土工试验都有不规范之处，综合分析，笔者倾向于第二种可能性。若是这种情况，应在室内资料整理与报告编写阶段，作异常值剔除。土工试验正确性直接关系到判断基坑安全性的问题，因此，土工试验测试数据必须是真实、准确，关键是规范取土和规范操作。
As a super high-rise building for the 2F foundation, from the data of geotechnical test, silty soil natural moisture content as high as 50.8 ﹪, natural void ratio and liquidity index close to silt, comparative data of regional water quality, obviously much higher. Cause analysis:①may be affected by the original foundation of the original river long-term soaking softening;②may be related to soil and soil test about the improper operation of sampling and soil test are irregularities, comprehensive analysis, the author tends to second possibilities. If this is the case, should be in the indoor data statistics and report writing stage, abnormal value elimination. Soil test accuracy is directly related to the judgment foundation pit safety problems, therefore, geotechnical test data must be true, accurate, the key is to standardize and regulate the operation of the soil.
　　(5)土层定名有误
( 5 ) soil name error
　　如某超高层建筑为2F基坑，从土层定名来看，将该沉积环境中的黏质粉土和淤泥质粘土夹黏质粉土，均定名为砂质粉土。错误的定名，影响了分析评价和降水方案的选择，若是砂质粉土，可以采用轻型井点或管井降水;而黏质粉土和淤泥质黏土夹黏质粉土，不宜采用降水，而是排水，即用集水井和明沟抽排即可。
As a super high-rise building foundation pit soil 2F, from the name of view, the sedimentary environment of clayey silt and silty clay with clayey silt, sandy silt is named. The wrong name, impact analysis and evaluation and selection of dewatering method, if sandy silt, can adopt the light well point or dewatering; and clayey silt and silty clay with clayey silt, unfavorable use precipitation, but drainage, which set well and ditch drainage can be.
　　(6)土的抗剪强度测试方法和取值的问题
( 6 ) soil shear strength test method and value problem
　　如何选择土的抗剪强度测试方法、合理取值和应用，应视土的性质、周边环境条件和深基坑开挖深度等具体情况选定。一般情况下，对饱和淤泥质等软土宜选择三轴不固结不排水(UU)强度试验，而对排水条件较好的粉砂土可采用三轴固结不排水(Cu)强度试验;但在实际工程中发现采用的是由地区经验得出来的固快值和快剪指标进行设计。
How to choose the soil shear strength test method, the reasonable value and application, should be treated soil properties, the surrounding environmental conditions and deep foundation pit excavation depth specific selected. In general, the saturated silt and soft soil should choose three axis undrained ( UU ) strength test, and silty soil better drainage conditions can be used three shaft consolidated undrained ( Cu ) strength test; but in practice using the solid fast values from the area of experience and quick shear index design.
　　(7)没有对地下管线作详细调查。
( 7 ) did not make a detailed survey of underground pipeline.
　　深基坑的环境保护是重要任务之一，在建筑密集的城区和公路边地下管线尤为突出，但勘察单位在基坑外侧多没有布置勘探点或很少对地下管线等进行调查，同时，地下管网建设缺乏系统规划，相互分隔，缺乏必要的信息共享和协调，形成各管各的局面。如某超高层建筑，为2F基坑，在对基坑周边钻孔灌注桩施工时，即使采用泥浆护壁的情况下，始终孔中返冒大量清水不得不停钻，后用挖掘机开挖，原来是打在一根废弃的涵管洞上，教训极其深刻。因此，在勘察中应重视对现行管线和废弃地下管线的详细调查。
Environmental protection of deep foundation pit is one of the important tasks for building, in dense urban and highway underground pipeline is particularly prominent, but the survey units in foundation pit lateral no arrangement of exploration or rarely on the underground pipeline survey underground pipeline construction, at the same time, the lack of systematic planning, separated from each other, the lack of necessary information sharing and coordination, the formation of each of the situation. As a super high-rise building foundation pit, 2F, in the construction of foundation pit of bored piles, even with slurry-supported conditions, always bore return water to stop drilling, with excavator excavation, it is playing in a deserted culvert hole, the lesson is extremely profound. Therefore, the investigation should be focused on the detailed investigation to current pipeline and abandoned underground pipeline.
　　(8)勘察成果报告。
( 8 ) report the results of the investigation.
　　深基坑属于高层、超高层建筑重要的不可分割一个部分，常在勘察成果报告中单列一节，发现存在的主要问题有:①在深基坑设计参数表中，对填土有的C、φ经验值没有提供;②土的抗剪强度多提供的是直剪固快资料;③使用不一，有的用直剪固快峰值，有的用勘察单位的推荐值，而有的设计则用自己的经验值;④提供的建筑抗浮设防水位相差很大;⑤分析评价力度不足，该写的不写，不该写的却占很大篇幅。
Deep foundation of high-rise buildings, important and indispensable one part, often in a separate report the results of the investigation, we found the main problems are: the design parameter of the deep foundation pit, to fill some C,φexperience value is not provided; the shear strength of soil to provide more direct shear solid fast data; the use is not a, some with direct shear solid soon peak, some reconnaissance units recommended values, and some design with their own experience; to provide building anti-floating waterlevel varies greatly; the analysis and evaluation of insufficient, the writing is not writing, the writing is not many pages.
　　如何编好这一章节，关键是要针对深基坑的周边环境、破坏后果严重程度、基坑深度、工程地质条件、水文地质条件等情况，至少应做到以下几点:①应列表阐明基坑设计参数，对填土可提供C、φ的经验值亦可;②重在评价，基坑围护方案点到为止;③建筑抗浮设防水位宜可取当地历年来的最高洪水位或地势较低地段，可按室外地坪标高确定；④须提出降(排)水或截水、如何使用设计参数、对施工中应注意的问题和监测等有关要求。
How to edit this section, the key is to the deep excavation of the surrounding environment, failure consequence severity, the depth of foundation pit, the engineering geological conditions, hydrogeological conditions, at least should do the following:①should list that design parameters of foundation pit, to provide C,φexperience can also fill;②on Evaluation of foundation pit supporting scheme, point; the building for anti-floating water level should be desirable local over the years in the highest flood level or low-lying areas, can be determined according to the elevation of outdoor terrace;④shall put down the ( row ) of water or water cutting, how to use the design parameters, the problems needing attention in the construction and monitoring and other relevant requirements.
　　二、原因浅析
Two, reason analysis
　　(1)质量意识淡薄，对深基坑的重要性认识不足;
( 1 ) the quality consciousness, lack of awareness of the importance of deep foundation pit;
　　(2)勘察有“重主楼轻基坑”的现象，缺少在沿基坑外侧布孔或调查;
( 2 ) the investigation " heavy building, light foundation " phenomenon, the lack of the foundation pit lateral hole or investigation;
　　(3)勘察市场竞争不规范，受工期短和勘察费用低等因素有关;
( 3 ) and the market competition is not standardized, the short duration and low cost factors survey;
　　(4)缺少刻苦学习和钻研业务，仅凭个人意愿行事。
( 4 ) the lack of hard study and studying business, only personal inclinations.
　　三、预防措施
Three, preventive measures
　　(1)对深基坑勘察重要性有足够的认识，对超大超深基坑事故的诱发或发生更应引起足够的重视;
( 1 ) have enough understanding of the importance of deep foundation pit exploration, on induction of super large and deep foundation pit accident or occurrence of more attention;
　　(2)规范勘察市场竞争;
( 2 ) for investigation of market competition;
　　(3)多学习规范，正确理解规范精神和严格执行规范的有关规定;
( 3 ) study the specification, the correct understanding of standard spirit and strictly implement the relevant provisions of specification;
　　(4)对深基坑事故应及时进行处理，总结经验与教训。
( 4 ) on the deep foundation pit accident should be timely treatment, summarize the experience and lessons.
　　四、几点体会
The experience of four, a few points
　　(1)深基坑是一个非常复杂的系统工程，开挖又是一个综合性的岩土工程问题，因此，不能简单地将深基坑支护结构作为临时性结构而降低勘察精度来考虑问题。
( 1 ) the deep foundation pit is a very complicated system engineering, excavation and geotechnical engineering problems, a comprehensive, therefore, cannot simply be deep foundation pit supporting structure as a temporary structure and reduce the accuracy of survey.
　　(2)深基坑勘察要求高于和严于浅基础和桩基础(无带地下室)的勘察。
( 2 ) was higher than that of deep foundation pit investigation requirements and strict in shallow foundation and pile foundation (no belt basement) survey.
　　(3)在地质(土质和水)和环境双重复杂条件下，对深基坑周边的外侧应布置勘探点，一般间距可控制在30m，并对深基坑周边环境条件应进行详细调查，将调查结果融入勘察成果报告，可供深基坑围护设计时参考。
( 3 ) in the geological ( soil and water ) and environment under complex conditions, shall be arranged on outer side of exploration of deep foundation pit, the general spacing can be controlled at 30m, and for the deep foundation pit surrounding environment should carry out a detailed investigation, the survey results to report the results of the investigation, which can offer reference for design of deep foundation pit support.
　　(4)深基坑事故，重在预防，关键要做到精心勘察，精心分析，测试数据真实、准确和正确评价。
( 4 ) on prevention of deep foundation pit accident,, key to do careful investigation, careful analysis, the test data real, accurate and correct evaluation.
　　(5)对山区滑坡、崩塌、泥石流、边坡失稳等地质灾害国家很重视，多有报导，但从勘察角度来研究深基坑问题却不多见。
( 5 ) on the mountain landslide, collapse, debris flow, slope instability and other geological disasters countries attached great importance, multiple reports, but from the perspective of exploration of deep foundation pit is not seen.
　　五、结论
Five, the conclusion
　　综上所述；本文结合深基坑岩土工程勘察成果报告和质量信息反馈等几个常见的勘察问题，分析了原因并相应作了处理。最后强调以预防为主，并明确提出了深基坑勘察应严于浅基础和桩基础(无带地下室)的勘察观点。
To sum up; this paper and report the results of quality information feedback and so on several common problems of deep foundation pit in the investigation of geotechnical engineering investigation, analyses the reasons and corresponding treatment. The emphasis on prevention, and clearly put forward the deep foundation survey should be strict in shallow foundation and pile foundation ( no basement with the survey point of view ).