【導(dǎo)讀】逐漸地變得重要。由于冰漬土以及含礫粘土的提出使土方工程地基勘察方法的綱要比傳統(tǒng)的勘察。或含礫粘土主要表現(xiàn)為低可塑性而且還含有從粘土到漂石的不同粒徑顆粒。大部分本地粘土與淤。泥質(zhì)土中包含不同比例的砂、礫石、卵石、漂石。顆粒級(jí)配控制著土體的行為，而且淤泥使土體。性質(zhì)易受天氣變化影響。國(guó)家檔案登記處2021年3月版的道路施工規(guī)范。壓法取樣通常將取樣器下沉至要求深度進(jìn)行取樣，并每間隔一米進(jìn)行取樣。內(nèi)應(yīng)盡量少擾動(dòng)，但級(jí)配變壞是很正常的，級(jí)配變壞將導(dǎo)致土樣分類不夠精確。一位有經(jīng)驗(yàn)的巖土工程師或工程地質(zhì)專家應(yīng)監(jiān)督取樣孔工作以及土樣的恢復(fù)。將采用無(wú)擾動(dòng)原狀土樣或高質(zhì)量土樣進(jìn)行試驗(yàn)。其必須在取樣區(qū)域安裝排水邊界以及水坑邊界或借用鉆孔以減少土樣的含水量?！裘軐?shí)度.加州承載比.MCV試驗(yàn)土樣小于20mm?！敉翗訙y(cè)試的準(zhǔn)備方法必須被明確規(guī)定，而且試驗(yàn)應(yīng)在指定試驗(yàn)室進(jìn)行。土樣擾動(dòng)常發(fā)生在搬運(yùn)過(guò)程中，破壞或者強(qiáng)度下降。

　　

【正文】 itability can be immediately obtained. TRIAL PITS The excavation of deep trial pits is often perceived as cumbersome and difficult and therefore not considered appropriate by design engineers. Excavation of deep trial pits in boulder clay soils to depths of up to 12m is feasible using benching techniques and sump pumping of groundwater. In recent years, IGSL has undertaken such deep trial pits on several large road ground investigation projects. The data obtained from these has certainly enhanced the geotechnical data and provided a better understanding of the bulk properties of the soils. It is remended that this work be carried out following pletion of the cable percussion boreholes and rotary core drill holes. The groundwater regime within the cut area will play an important role in governing the feasibility of excavating deep trial pits. The installation of standpipes and piezometers will greatly assist the understanding of the groundwater conditions, hence the purpose of undertaking this work late on in the ground investigation programme. Large representative samples can be obtained (using trench box) and insitu shear strength measured on block samples. The stability of the pit sidewalls and groundwater conditions can also be established and pared with levels in nearby borehole standpipes or piezometers. Over a prominent cut area of say 500m, three deep trial pits can prove invaluable and the spoil material also used to carry out smallscale paction trials. From a value engineering perspective, the cost of excavating and reinstating these excavations can be easily recovered. A provisional sum can be allocated in the ground investigation and used for this work. 浙江工業(yè)大學(xué)畢業(yè)設(shè)計(jì)外文翻譯 7 QUALITY LARGE DIAMETER ROTARY CORE DRILLING This system entails the use of large diameter rotary core drilling techniques using air mist or polymer gel flush. Triple tube core drilling is carried out through the overburden soils with the recovered material held in a plastic core liner. Core recovery in low plasticity boulder clay has been shown to be extremely good (typically in excess of 90%). The high core recovery permits detailed engineering geological logging and provision of samples for laboratory testing. In drumlin areas, such as those around Cavan and Monaghan, IGSL has found the use of large diameter polymer gel rotary core drilling to be very successful in recovering very stiff / hard boulder clay soils for deep road cut areas (where cable percussion boreholes and trial pits have failed to perate). Insitu testing (vanes, SPT’s etc) can also be carried out within the drillhole to establish strength and bearing capacity of discrete horizons. Large diameter rotary drilling costs using the aforementioned systems are typically 50 to 60% greater than conventional HQ core size, but again from a value engineering aspect can prove much more worthwhile due to the quality of geotechnical information obtained. COMPACTION TRIALS The undertaking of smallscale paction trials during the ground investigation programme is strongly advised, particularly where ‘marginally suitable’ soils are present in prominent cut areas. In addition to validating the laboratory test data, they enable more realistic planning of the earthworks and can provide considerable cost savings. The paction trial can provide the following: ? Achievable field density, remoulded shear strength and CBR ? Establishing optimum layer thickness and number of roller passes ? Response of soil during paction (static v dynamic) ? Monitor trafficability amp。 degree of rutting. A typical size test pad would be approximately 20 x 10m in plan area and up to in thickness. The selected area should be close to the cut area or borrow pit and have adequate room for stockpiling of material. Earthwork plant would normally entail a tracked excavator (CAT 320 or equivalent), 25t dumptruck, D6 dozer and either a towed or selfpropelled roller. Insitu density measurement on the pacted fill by nuclear gauge method is remended as this facilitates rapid measurement of moisture contents, dry and bulk densities. It also enables a large suite of data to be generated from the pacted fill and to assess the relationship between degree of paction, layer thickness and number of roller passes. Both disturbed and undisturbed (U100) samples of the pacted fill can be taken for laboratory testing and validation checks made with the field data (particularly moisture contents). IGSL’s experience is that with good planning a smallscale paction trial takes two working days to plete.