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Different injection material types were tried in the injection of soft clay, such as lime (L), silica fume (SF), and leycobond-h (LH). In this study, experiments were made to study the effect of injection on soft clay consolidation settlement. A sample of natural soft clayey soil was investigated in the laboratory and the sample was injected with each of the grout materials used, L, SF, L + SF, and L + SF + LH. A 20 cm3 of each slurry grout was conducted into the soil, which was compacted in California Bearing Ratio (CBR) mold and cured for 7 days, and then the sample was loaded to 80 N load by a circular steel footing 60 mm in diameter. The settlement was recorded. The sample of each slurry grout, which provided minimum settlement, was chosen (L + SF + LH). To reduce soft clay settlement before and after footing construction, four cases were investigated. The impact of injection hole spacing and grout depth was studied. It was discovered that injecting a slurry of (L + SF + LH) into the soft clay beneath or surrounding the footing increased bearing capacity by 5–88%. Due to the shape of shear failure of the soft clay around the footing, grouting near the footing at a distance of 0.5 diameter of the footing is more effective than grouting at a distance of 1.0 diameter of the footing, and grouting near the footing at a distance of 0.5 diameter of the footing is more effective than grouting at a distance of 1.0 diameter of the footing.

This paper deals with testing defected model piles in the soil in order to study their behavior. In this respect, the results of model pile tests are discussed either geotechnically or structurally according to the type of failure.   Two parameters were studied in order to evaluate the general behavior of defective piles. These parameters include the defect location and the defect type for floating and end bearing pile. The results of the experimental work indicated that the critical case for floating pile is seen to be when the defect of (5%) at the first third of the pile length at which the decrease in the bearing capacity is about (21%), while the decrease in the bearing capacity is found to be (14%) and (10%), when the defect is at the middle and the lower third of the pile length, respectively. The decrease in the bearing capacity for floating pile is found to be (31%) and (21%) for void and neck defect, respectively, while the decrease in the bearing capacity for end bearing pile is found to be (43%) and (52%) for void and neck defect, respectively.

In order to understand the effect of (length of pile / diameter of pile) ratio on the load carrying capacity and settlement reduction behavior of piled raft resting on loose sand, laboratory model tests were conducted on small-scale models. The parameters studied were the effect of pile length and the number of piles. The load settlement behavior obtained from the tests has been validated by using 3-D finite element in ABAQUS program, was adopted to understand the load carrying response of piled raft and settlement reduction. The results of experimental work show that the increase in (Lp/dp) ratio led to increase in load carrying capacity by piled raft from (19.75 to 29.35%), (14.18 to 28.87%) and (0 to 16.49%) , the maximum load carried by piles decrease from(9.1 to 22.72%), (15.79 to 47.37%) and (44 to 81.05%) and the response of settlement piled raftdecrease from (16.67 to 23.33%), (9.09 to 39.39%) and (30%) with increase the number of piles from 4 to (6 and 9) and (length of pile / diameter of pile) ratio increase to (14.14 and 21.2), respectively. The numerical and model test results are found to be in a good agreement.

Many problems are facing the installation of piles group in laboratory testing and the errors in results of load and settlement are measured experimentally may be happened due to select inadequate method of installation of piles group. There are three main methods of installation in-flight, pre-jacking and hammering methods. In order to find the correction factor between these methods the laboratory model tests were conducted on small-scale models. The parameters studied were the methods of installation (in-flight, pre-jacking and hammering method), the number of piles and in sandy soil in loose state. The results of experimental work show that the increase in the number of piles value led to increase in load carrying capacity of piled raft and decrease in settlement value for three methods of installation. The response of increases load capacity  for hammering method is the same value of pre-jacking method at the number of piles less than (N=2), while when the number of piles are beyond (N=3 to 9). The load capacity of hammering method is more than pre-jacking method and the correction factor of method of installation depend on the type of method of installation and the piles number. The increase in carrying capacity by hammering method is due to mobilize the dynamic soil structure interaction (soil-pile and pile-pile interaction) and the change in properties for surrounding soil for loose state of sand is more effective than static soil structure interaction mobilize by pre-jacking method. The correction factor of increase in load capacity and the correction factor of the percentage of settlement reduction for pre-jacking and hammering methods are compared with in-flight method of installation  are changed with the number of piles and these values are increased with increasing the number of piles.