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[Econf_Moderator]

亲爱的所有:�


以下是来自地质技术顾问Jaydeep Wagh先生的初步说明，他是会议的主题专家之一


问候,
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高层建筑的选址
高层建筑通常可以在任何地下条件下的任何地点建造。�However, certain difficult or complex subsurface conditions at some sites may render construction of high rise buildings impractical with respect to time and cost.� These difficult subsurface conditions may include presence of competent strata at relatively deep depths (>60m) or due to presence of miscellaneous fill with boulders, which make it difficult for piling equipment to penetrate to competent strata.� A comprehensive geotechnical engineering program combined with extensive geotechnical experience of high rise buildings is essential in arriving at safe and cost effective foundation design.
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岩土工程勘察方案:
一个完整的岩土工程调查程序是达到设计弹簧常数和/或高层建筑基础设计的必要先决条件。一个适当的岩土工程调查计划也可能有助于显著降低基础成本，同时确保安全的基础
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不能为高层建筑场地规定通用的详细岩土勘察方案，因为这显然取决于建筑物的类型、楼层数、地下室数量(如果有的话)和地下条件。�Typically, boreholes for a high rise building are spaced at every 25m to 30m and are extended to 1.5 times the width of foundation or 5m into relatively incompressible strata and atleast 5 times pile diameters in case of pile foundations.� At a minimum SPT tests are generally conducted in soil and soft rock, while rock coring operations are conducted in hard rock.� A detailed custom geotechnical program can be chalked out after initial boreholes are available and a foundation system type has been selected.� Detailed tests including pressuremeter tests, plate load tests, or pile load tests can then be conducted.� If local experience is available, a detailed geotechnical investigation program may be specified right from the beginning.� However, it is prudent to still study initial borehole logs to see if any modification to the geotechnical investigation program is required.
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桩筏基础:
如果在筏子奠基层遇到相对合适但不完全合适的地层，则可以考虑采用桩筏基础来代替完整的桩基础。-桩筏基础的效率将取决于与桩尖水平附近的土壤/岩石相比，筏子创始水平的土壤/岩石的相对刚度。值得注意的是，一定程度的阻力总是由桩帽或桩筏下的土壤/岩石提供的。�However, the effort required in analyzing this available resistance may not be justified if the soils at pile cap/raft level are relatively much softer.� A typical example of this is a building constructed in soft marine clay areas when the pile tip is extended to underlying hard rock.� The contribution of a pile cap or raft portion of the piled raft in carrying loads may range from negligible (as mentioned above) to even 90% in some cases.
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典型的允许变形通常由结构的允许差异沉降决定。�Differential settlements limits as specified in several country codes for raft foundations can also be applied to piled rafts.� Typical permissible limits range from L/660 for spread foundations to L/400 for raft foundations.� Some country codes also specify a permissible for total maximum deformations, for eg. 75mm in IS1904.
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一种更激进的桩筏设计形式，由于岩土有限元程序的发展，近年来已变得相当流行，是减沉桩。�This specific application can be used where a conventional raft only foundation would have adequate factor of safety against shear failure, but cannot be utilized as it does not meet the permissible total/differential settlement criteria.� Few piles are then added beneath the raft at strategic locations solely to reduce the total/differential settlements to within permissible limits.
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桩荷载试验对桩筏系统的设计是必不可少的。�A pile load test not only provides ultimate pile capacity, but also provides the pattern of pile load v/s. pile settlement, which is essential in deformation analysis of a piled raft.� Test pile should be conducted using same equipment and methods as for final working piles.����
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人工设计方法可用于荷载分布相对均匀的常规建筑物的岩土工程分析。然而，有限元软件通常是高层建筑桩筏分析的必要条件，也被认为更准确。�������������
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Jaydeep Wagh�

通过电子邮件发布

[苏拉]

土壤调查及报告概要
1.高层建筑要求较高的土壤调查
2.的确，该结构建立在坚硬的岩石上，比其他正常的建筑要深得多，后者的深度小于o>
3.勘探要求N/ SPT, TCR, SCR, RQD
4.N适用于侵彻300mm时标准侵彻试验中测量相关击数
5.越低渗透的N值越高，土壤类型越好
6.但是，它适用于粘性土，而不适用于的岩石
7.取岩样作为岩心钻取物
8.TCR表示核心总采收率
9.SCR代表固体核心恢复
10.计数/测量超过100mm的岩心，使总固体回收率
11.将总结出来的岩芯块与岩芯总采收率进行比较
12.RQD表示岩石质量的指定，计算比率SCR除以TCR
13.RQD越高，岩石越好
14.在某些病例中，超过80%的RQD
15.软岩石给出较小的值
16.其他测试包括导热系数和电阻率测试
17.电导率以及电阻率测试
18.当筏桩周围涉及土壤时，研究与Atterberg极限相关的土壤参数
19.还进行了其他各种试验，但在前面中，对可能靠在坚硬岩石上的深地基或桩基进行了突出的研究
20.土壤调查和测试报告应是描述性的，给出所采用的完整测试程序和相关表格结果和相关建议，使设计工程师能够根据所有指示参数制定基础初步工作
21.所有假设都应该明确地包括在清晰的沟通
22.报告的所有限制都应精心定义
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[P.K.Mallick]

[苏拉]

岩石/抗压强度/BS 5930

1. 极强/锤击时岩石环/>200MN/m^2
   
2. 非常坚固/仅用重型锤击碎芯/100-200MN/m^2
   
3. 坚固/重锤击碎/ 50-100MN/m^2
   
4. 中等强度/手握时锤击破碎/12.5-50MN/m^2
   
5. 中等强度/薄板或边缘被手用力压碎/5-12.5MN/m^2
   
6. 弱/砾石大小的块体被手压碎/1.25-5MN/m^2
   
7. 非常弱/砾石大小的块压碎在手指和拇指之间/<1>
   
8. RQD 70/75可能被认为是硬范围

细粒度的

1. 50/非常密集
   
2. 击数30-50/密集

粘性土

1. 不排水抗剪强度>300 KN/m^2/硬

[苏拉]

岩土工程

1. 虽然这是对很久以前在普通论坛上发表的评论的重复，但建议所有工程师不要避免土壤勘探解释
   
2. 人们注意到，工程师们并不感兴趣地研究材料测试实验室提交的土壤报告
   
3. 诚然，土壤报告文件是大量的页，但如果是由一些专业实验室发布的信息非常丰富
   
4. 没有清楚的了解报告，工程师也不能确定设计理念，施工现场工程师不能理解处理土工程
   
5. 在土力学方面可以有许多合格的大师，但在这次会议上讨论的相关主题并不多
   
6. 我认为土壤工程可以帮助所有工程师做好基础设计和现场施工
   
7. 即使是设计工程师也不会费心去彻底了解报告，而是继续进行设计，这种情况导致在现场开始工作时，有时会改变设计
   
8. 在设计和施工之前，应清楚地了解土壤参数