Effect Of Shear Strength Parameters In Residual Soils On Slope Failures

Faktor utama yang menyebabkan cerun runtuh di tanah baki adalah pengurangan kekuatan ricih akibat tanah menjadi tepu semasa musim hujan. Banyak cerun yang direkabentuk gagal dalam beberapa tempoh selepas ianya dibina. Oleh kerana kekuatan ricih sentiasa berubah-ubah, adalah perlu untuk kajian dibuat ke atas perubahan tersebut dan menentukan nilai batasan bawah untuk kegunaan merekabentuk cerun. Sampel tanah terganggu diambil dari cerun runtuh di Pulau Pinang dan Baling. Sejumlah 227 pasangan kejeliketan dan sudut geseran ricih berkesan diperolehi dari tanah cerun runtuh dan ianya diuji menggunakan ujian kotak ricih terkukuh salir dalam keadaan tanah terendam. Kedua-dua data kejeliketan dan sudut geseran berkesan diasingkan dan dibahagikan secara rawak kepada 2 kumpulan iaitu data model latihan 70%, dan data cerapan validasi 30%, menggunakan perisian Matlab. Dengan menggunakan ujian petunjuk prestasi ke atas 2 kumpulan data tersebut secara taburan jenis Normal, Weibull, Gamma dan Beta, didapati taburan Normal ialah taburan yang terbaik. Menggunakan nilai purata dan sisih piawai dari data model latihan, data ramalan validasi diwujudkan melalui perisian Matlab. Untuk tujuan validasi, dengan menggunakan ujian petunjuk prestasi, data cerapan validasi dibandingkan dengan data ramalan validasi. Di antara objektif utama penyelidikan ini adalah untuk menentukan nilai batasan bawah kekuatan ricih tanah yang diambil dari cerun runtuh. Dari taburan jenis Normal, nilai batasan bawah untuk c‟ = 0.86 kN/m2 dan ø‟=16.21o, nilai purata c‟ = 14.54 kN/m2 dan ø‟ = 31.31o manakala nilai batasan atas untuk c‟ = 44.88 kN/m2 dan ø‟ = 49.46o ditemui. Berdasarkan kepada statistik untuk taburan jenis Normal, adalah didapati bahawa hampir 95 % dari data berada diantara nilai batasan bawah dan nilai batasan atas dengan nilai purata berada ditengah-tengah taburan tersebut. Menggunakan perisian SLOPE / W berdasarkan keratan lintang cerun yang tidak gagal dan menggunakan nilai batasan bawah yang ditemui, adalah didapati nilai faktor keselamatan cerun adalah kurang dari 1. Ini mengesahkan bahawa nilai batasan bawah yang ditemui adalah betul. Nilai faktor keselamatan cerun adalah melebihi dari 1 apabila nilai purata dan nilai batasan atas digunakan ________________________________________________________________________________________________________________________ The main factor causing slope failures in residual soils is the reduction of shear strength parameters of the slope as the soil becomes saturated during the rainy seasons. Many engineered slopes failed some periods after their completion. Since the shear strength parameters of the residual soil are highly variable, there is a need to study their variability and thus determine the lower bound values to be used in the slope design. Disturbed soil samples were taken at the slope failures in Penang and Baling. A total of 227 pair of effective cohesion and fiction angle data were obtained from slope failures and tested under submerged condition using consolidated drained shear box tests. These effective cohesion and fiction angle were separated and both of them were divided randomly into 2 subset data namely model training data 70%, and observed validation data 30%, using the Matlab software. By conducting performance indicators on the 2 subset data using Normal, Weibull, Gamma and Beta distributions, Normal distribution was found to be the best fit distribution. Using the means and standard deviations of the model training data, predicted validation data were created using Matlab software. For validation purposes, performance indicators were conducted on both the observed and predicted validation data based on Normal distribution. Among the main objective of the research is to determine the lower bound values of the effective shear strength parameters of soils taken from slope failures. From the normal distribution curves of the model training data, the lower bound value of c‟ = 0.86kN/m2 and ø‟ = 16.21o, the mean value of c‟ = 14.54 kN/m2 and ø‟ = 31.31o while the upper bound value of c‟ = 44.88 kN/m2 and ø‟ = 49.46o were found. Based on the statistics of normal distribution, most the data of about 95 % will fall between the lower bound and upper bound values with the mean values in the middle. These lower values were tested using SLOPE / W software based on typical cross sections of un-failed slopes and the factor of safety was less than 1. This confirmed the lower bound values. The values of factor of safety were greater than 1 when the mean and upper bound values were used

Repair of major road embankment failure using reinforced earth (re) wall

A case history of repair works of major road embankment failure along Genting Highlands to Bukit Cincin, Pahang is presented. Failures at 10 locations along Genting Highlands to Bukit Cincin road occurred on 30th October 1997 during the monsoon seasons. The repair works at Location 1 using reinforced earth wall was considered since there was enough space available at the downslope section and also the soil at the downslope section of the failed embankment was strong enough to construct the wall safely. This paper fully explained the details remedial works using reinforced earth wall at Location 1

Evaluation of shear strength parameters using shear box tests for slope failures in Penang / Mohamad Zain Hashim, Damanhuri Jamalludin and Muhammad Hafeez Osman

On 11th December 1993, Highland Tower near Hulu Kelang, Selangor toppled due to slope failure causing 48 residents to be killed. It became the worst nightmare to all Malaysians especially to the residents of the un-failed nearby tower as well as in the engineering lines. Since then, many more slope failures have occurred in Malaysia yearly during the rainy seasons. Hence, slope failure has been ranked as the worst natural disasters in Malaysia. Therefore, the studies on slope failures are becomes more important. Slope failure, also referred to as mass wasting, is the down slope movement of rock debris and soil in response to gravitational stresses. There are many factors affecting slope failures such as weaknesses in the composition or structure of the rock or soil; variation in conditions such as change in rainfall, unorganized drainage or surface stability (removal of vegetation). Among these factors, rainfall, earthquake and human activities are important starter factors that are causing slope failures to occur. This study is to determine the soil shear strength under saturated condition along Teluk Bahang-Balik Pulau road Penang. Saturated shear box tests were conducted to determine the shear strength for soil samples taken from slope failure locations

Pull out characteristics of soil nails in Pahang / Damanhuri Jamalludin ...[et al.]

A total of 45 locations of slope failures occurred along Jalan Baru Gap to Fraser Hill, Pahang. Of the 45 locations of slope failures, only 31 locations were repaired using soil nails. At each location, only one pull out test was carried out. This study involved the results of the pull out tests at all the 31 locations and the results were obtained from Public Works Department, K.L. The maximum pull out load during the test was 90 kN and the displacement at 90 kN load must be less than 10mm for the test to be considered satisfy the specifications. The main purpose of this study is to determine the characteristics of the pull out test on soil nail and the interaction between the soil nail and the soil

Effective shear strength parameters of soil samples taken from slope failure along the KULIM – BALING road / Damanhuri Jamalludin... [et al.]

Slope failures always occur in Malaysia especially during the monsoon seasons between October and January every year causing fatalities and damages to properties. The main factors causing the slope failure to occur are reduction of the shear strength parameters and loss of negative suction due to saturation of the slope. The objective of this study is to determine the effective shear strength parameters of the soil taken at slope failure using consolidation drain (CD) shear box and also to determine the factor of safety using SLOPE/W software. The soil samples were tested under submerged condition. The minimum value of effective shear strength parameters obtained from the CD shear box tests were c’ = 0 kN/m2 and ø’ = 47.30 while the maximum value of c’ = 30.2 kN/m2 and ø’ = 35.6 0. The FOS varied from 0.377 to 0.749 with minimum value of factor of safety was 0.377. When using SLOPE/W software on a stable slope cross section having minimum value of effective shear strength parameters, the minimum value of factor of safety was less than 1 indicating that the slope had already failed

Geotechnical properties of Alor Setar clay along Jalan Kuala Kedah-Hutan Kampung / Mohd Farid Ahmad … [et al.]

This research paper is to study the geotechnical properties of clay soil at Alor Setar. The main purpose of this study is to obtain design parameters for Alor Setar clay soil. Based on the study, a local database of design parameters characteristics are presented with some empirical or analytical correlation established to estimate SPT value, index properties and mechanical properties of Alor Setar clay. The data were analyzed and the correlation of each parameter with depth were obtained. Conclusions have been made based on the evaluation and the Alor Setar clay were found to have high moisture content, plastic limit, liquid limit and compression index. The soft clay depth generally down to 8 meter. From the OCR value the clay was found to be lightly over consolidated. Based on Cc value, the compressibilty potential of Alor Setar clay is high. It is hoped that the outcome from this research work can contribute for future reference

Evaluation of shear strength parameters using shear box tests for slope failures in Penang / Mohamad Zain Hashim, Damanhuri Jamalludin, Muhammad Hafeez Osman

On the 11th December 1993, Highland Tower near Hulu Kelang, Selangor toppled due to slope failure causing 48 residents was killed. It became the worst nightmare to the all Malaysian especially to those who are the residents of the un-failed nearby tower as well as in the engineering lines. Since then, many more slope failures occurred in Malaysia yearly during the rainy seasons. Hence, slope failures ranked among the worst natural disaster occurring in Malaysia, studies on the slope failures are becoming important. Therefore, it is very important for us to know the main causes that are causing the occurrences of landslides or failure in slopes in Malaysia. Slope failure, also referred to as mass wasting, is the down slope movement of rock debris and soil in response to gravitational stresses. There are many factors affecting slope failures such as weaknesses in the composition or structure of the rock or soil; variation in conditions such as change in rainfall, unorganized drainage or surface stability (removal of vegetation). Among these factors, rainfall, earthquake and human activities are important starter factors that are causing slope failures to occur. This study is to determine the soil shear strength under saturated condition along 2 roads in Penang Island namely along Teluk Bahang - Balik Pulau road and along Teluk Kumbar - Gertak Sanggul road. Saturated shear box tests were conducted to determine the shear strength for soil samples taken from slope failure locations. Histograms of the cohesion and friction angle were plotted along the 2 roads and their average values were determined. It was found that the ranges average value of cohesion and friction angle along Teluk Bahang - Balik Pulau road are higher than that along Teluk Kumbar - Gertak Sanggul road

Evaluation of slope failure based on soil physical properties and shear strength parameters for tropical residual soil / Intan Shafika Saiful Bahri, Damanhuri Jamalludin, Roslan Zainal Abidin

In Malaysia, slope failure normally occurs during rainy seasons and almost no slope failures were reported during dry seasons. This is mainly due to the effect of water that flows through soil. When the soil becomes saturated, negative suction will be destroyed, the shear strength of soil was reduced thus causes slope instability. In other words, cause of slope failures are closely related to the additional weight of rainwater retained in the soil slope, causing the slope to fail. The main objective of this research is to determine the relationship between soil shear strength using shear box tests and ROM value obtained from particles size distribution curves. ROM value was obtained using ROM equation based on the percentages of sand, silt and clay. A total of 20 slope failure locations were selected at the specified area. Five slope failure locations were selected from Baling, Kedah and another five locations were selected in Gerik, Perak. Additionally, another 10 slope failure locations were selected along Route 6, Balik Pulau, Penang. Soil samples were collected at the failed and un-failed slope section next to the failed one. Seven soil samples were collected for each slope failure location. Soil samples were collected at about 100mm below the existing ground level. Bulk density was determined using field bulk sampler. Shear box tests under saturated at bulk density conditions and sieve with hydrometer tests were conducted. In conclusion, it was found that the soil shear strength increases as the ROM value decreases