Determination of soil moisture content and density using electrical resistivity values

Ciri geoteknik merupakan elemen penting dalam kerja-kerja rekabentuk dan pembinaan kejuruteraan awam. Pada masa lalu, ciri geoteknik diperolehi menggunakan teknik penyiasatan tapak konvensional melalui penggerudian dan pengorekan. Kaedah tersebut mempunyai beberapa batasan dari segi kos, masa dan liputan data. Maka kajian ini mewujudkan penentuan ciri geoteknik asas (kandungan lembapan dan ketumpatan) menggunakan korelasi data geofizik terutamanya nilai keberintangan elektrik. Kajian ini dijalankan pada tanah pasir dan pasir berkelodak dengan tahap ketumpatan yang berbeza melalui ujikaji makmal, model fizikal lapangan dan lapangan. Sampel tanah diuji di dalam makmal untuk pencirian geoteknik dan ujian keberintangan kotak tanah masing-masing berpandukan BS 1377 (1990) dan AASHTO (T-288-91). Dua model fizikal lapangan homogen pasir dan pasir berkelodak diuji menggunakan keberintangan elektrik dan pengelasan tanah. Pengesahan keputusan dibuat melalui ujikaji lapangan di Kuala Kangsar (pasir) dan Lenggong (pasir berkelodak). Analisis data dibuat menggunakan kaedah statistik dan perisian keberintangan komersial iaitu Statistical Package for the Social Sciences (SPSS), Microsoft excel dan RES2DINV. Ujikaji makmal mendapati bahawa perkaitan antara nilai keberintangan elektrik tanah dengan kandungan lembapan dan ketumpatan adalah pada korelasi sederhana hingga sangat kuat (r = -0.405 – 0.949). Satu siri nilai keberintangan elektrik tanah telah dihasilkan, justeru membolehkan penentuan cirri asas geoteknik tanah menggunakan persamaan statistik yang dihasilkan. Ciri asas geoteknik lapangan terutamanya kandungan lembapan dan xxii ketumpatan boleh diperolehi menggunakan persamaan statistik dengan menggunakan faktor pekali (C) yang dihasilkan daripada ujikaji model fizikal lapangan. Didapati nilai keberintangan elektrik tanah adalah berbeza dalam keadaan longgar (L) dan tumpat (D) dengan pekali penentuan, R2 kandungan lembapan dan ketumpatan diperolehi pada nilai 0.7530 – 0.9706 dan boleh digunakan untuk anggaran melalui penggunaan faktor pekali (C) menggunakan persamaan berikut: MC(L) = 591.61ρ-0.557, MC(D) = 723.64ρ-0.723 dan ρbulk(L) = 5.3011ρ-0.193, ρbulk(D) = 3.3351ρ-0.109 untuk pasir dan MC(L) = 186.81ρ-0.265, MC(D) = 259.01ρ-0.373, ρbulk(L) = 0.376ln(ρ) + 4.3043 dan ρbulk(D) = 4.591ρ-0.138 untuk pasir berkelodak. Pengesahan keputusan di Kuala Kangsar dan Lenggong mendapati bahawa teknik ini boleh diguna pakai dalam menentukan kandungan lembapan dan ketumpatan tanah lapangan yang efisyen kerana pantas, ekonomi, sebaran data yang luas serta bersifat lestari dengan alam sekitar

Coagulation-Flocculation of Leachate by Using Single Coagulant Made from Chemical Coagulant (Polyaluminium Chloride) and Natural Coagulant (Tapioca Flour)

Application of coagulation and flocculation in leachate treatment is common nowadays. Chemical coagulant is commonly applied compared to natural coagulant. Thus, this study compared the effectiveness of landfill leachate treatment by single coagulant which are chemical and natural coagulant through the removal of suspended solid (SS), sludge settling rate and sludge volume index. The experiment was carried out using standard jar test method and raw leachate sample was collected from Landfill Simpang Renggam. The chemical coagulant used was polyaluminium chloride and natural coagulant was Tapioca flour. Tapioca flour has characteristic as coagulant where it has sticky characteristic that can remove pollutant in leachate without leaving any side effects latter and it is available in abundance, cheaper, and environmentally friendly. Result of this study shown that, the optimum dosage and pH of PAC was 3g/L at pH 8 and for tapioca flour was 1g/L at pH 4. The percentage removal by PAC as in term of removal of suspended solid, sludge volume index and sludge settling rate were 94%, 5273 mL/gm and 1.58 cm/min, respectively. While, for tapioca flour there was minimal sludge formation and the removal of SS was 13.3%. The particles size for sludge leachate after treatment for optimum dose was in range of 20µm and the floc were arranged compacted, and shaped elongated. Hence, this study shows that PAC is more effective than Tapioca flour as single coagulant in terms of sludge volume index, sludge settling rate, removal of suspended solid and particle size of sludge

Soil resistivity influence due to the different utilization of electrical resistivity array

Electrical resistivity method (ERM) was increasingly adopted as an alternative tool in shallow subsurface exploration by the geotechnical engineers. This study presents the influence of soil electrical resistivity value (ERV) due to the different types of electrical resistivity array used in practice. The dissimilarity of ERV has always become a popular argument by engineers to the geophysicist due to its less fundamental knowledge of electrical resistivity method. From past experienced, the fundamental of ERM was less being exposed by the engineer thus creating several black boxes of the ERM basic theory which importantly required during the data acquisition and processing stages. Hence, the result produced from the ERM was difficult to deliver in a sound of definitive ways due to lack of knowledge and experienced of most engineers. Hence, this study presents the influence of soil ERV due to the different types of array used with particular reference to Wenner, Schlumberger, Dipole-dipole and Pole-dipole. A line of electrical resistivity imaging was performed on small embankment of lateritic soil in loose condition with different types of array using ABEM SAS (4000) equipment set. Three in line of soil samples were tested for moisture content (w) test immediately after the electrical resistivity data acquisition was completely measured. Moreover, particle size distribution test using dry and wet sieve was also being performed in order support to the ERV findings. It was found that the ERV was different for each types of array used even it was performed on the same particular location of the survey line. However, it was found that there is a consistent relationship between ERV and moisture content results which can be represent by ERV ∞ 1/w. Hence, it was found that ERV can be influenced by types of array used during the field measurement despite of the physical and chemical influences. Each types of array were applicable in subsurface profile investigation which normally subjected to the several considerations such as object target and the maximum depth of interest investigated

General Relationship between Field Electrical Resistivity Value (ERV) and Basic Geotechnical Properties (BGP)

Electrical resistivity technique is a popular alternative method used in geotechnical soil investigations. Most past applications have been particularly in the area of subsurface ground investigations such as to locate boulder, bedrock, water table, etc. Traditionally, this method was performed by a geophysicist expert for data acquisition, processing and interpretation. The final outcome from the electrical resistivity technique was an anomaly image which used to describe and conclude the particular soil condition measured. The anomalies highlighted uncertainties on the nature of soil that was often variable and depended on each particular site condition that gave a site dependent soil electrical resistivity value (ERV). Hence, this study demonstrates a relationship between ERV (ρ) and some of the basic geotechnical properties (BGP) such as soil moisture content (w), grain size of geomaterial (CS or FS), density (ρbulk and ρdry), porosity (η), void ratio (e) and Atterberg limit (AL). Different soil samples were collected and tested under field and laboratory conditions to determine basic geotechnical properties immediately after the field electrical resistivity method was performed. It was found that the electrical resistivity value was different for number of soils tested and was relatively subjective to variations in the geotechnical properties. In other words, electrical resistivity value was greatly influenced by the geotechnical properties as the ERV was higher due to the lower moisture content, void ratio and porosity with a higher value of soil density and vice versa. The relationship of ERV and BGP can be described by ρ α 1/w, ρ α CS, ρ α 1/FS, ρ α ρbulk/dry and ρ α 1/AL. Hence, it was shown that behaviour of ERV was significantly influenced by the variation of basic soil properties and thus applicable to support and enhance the conventional stand alone anomaly outcome which is traditionally used for interpretation purposes

The influences of basic physical properties of clayey silt and silty sand on its laboratory electrical resistivity value in loose and dense conditions

Non-destructive test which refers to electrical resistivity method is recently popular in engineering, environmental, archaeological and mining studies. Based on the previous studies, the results on electrical resistivity interpretation were often debated due to lack of clarification and evidences in quantitative perspective. Traditionally, most of the previous result interpretations were depending on qualitative point of view which is risky to produce unreliable outcomes. In order to minimise those problems, this study has performed a laboratory experiment on soil box electrical resistivity test which was supported by an additional basic physical properties of soil test like particle size distribution test (d), moisture content test (w), density test (ρbulk) and Atterberg limit test (LL, PL and PI). The test was performed to establish a series of electrical resistivity value (ERV) with different quantity of water content for clayey silt and silty sand in loose and dense condition. Apparently, the soil resistivity value was different under loose (L) and dense (C) conditions with moisture content and density variations (silty SAND = ERVLoose: 600 - 7300 Ωm & ERVDense: 490 - 7900 Ωm while Clayey SILT = ERVLoose: 13 - 7700 Ωm & ERVDense: 14 - 8400 Ωm) due to several factors. Moreover, correlation of moisture content (w) and density (ρbulk) due to the ERV was established as follows; Silty SAND: w(L) = 638.8ρ-0.418, w(D) = 1397.1ρ-0.574, ρBulk(L) = 2.6188e-6E-05ρ, ρBulk(D) = 4.099ρ-0.07 while Clayey SILT: w(L) = 109.98ρ-0.268, w(D) = 121.88ρ-0.363, ρBulk(L) = -0.111ln(ρ) + 1.7605, ρBulk(D) = 2.5991ρ-0.037 with determination coefficients, R2 that varied from 0.5643 – 0.8927. This study was successfully demonstrated that the consistency of ERV was greatly influenced by the variation of soil basic physical properties (d, w, ρBulk, LL, PL and PI). Finally, the reliability of the ERV result interpretation can be enhanced due to its ability to produce a meaningful outcome based on supported data from basic geotechnical properties

Time-lapse resistivity investigation of salinity changes at an ex-promontory land: a case study of Carey Island, Selangor, Malaysia

Time-lapse resistivity measurements and groundwater geochemistry were used to study salinity effect on groundwater aquifer at the ex-promontory-land of Carey Island in Malaysia. Resistivity was measured by ABEM Terrameter SAS4000 and ES10-64 electrode selector. Re�lationship between earth resistivity and total dissolved solids (TDS) was derived, and with re�sistivity images, used to identify water types: fresh (ρe > 6.5 � m), brackish (3 � m < ρe < 6.5 � m), or saline (ρe < 3 � m). Long-term monitoring of the studied area’s groundwater quality via measurements of its time-lapse resistivity showed salinity changes in the island’s groundwater aquifers not conforming to seawater-freshwater hydraulic gradient. In some aquifers far from the coast, saline water was dominant, while in some others, freshwater 30 m thick showed ground�water potential. Land transformation is believed to have changed the island’s hydrogeology, which receives saltwater pressure all the time, limiting freshwater recharge to the groundwater system. The time-lapse resistivity measurements showed active salinity changes at resistivity-image bottom moving up the image for two seasons’ (wet and dry) conditions. The salinity changes are believed to have been caused by incremental tide passing through highly porous material in the active-salinity-change area. The study’s results were used to plan a strategy for sustainable groundwater exploration of the island

Modelling technique for the assessment of the sub-soil drain for groundwater seepage remediation

Groundwater simulation technique was carried out for examining the performance of sub-soil drain at problematic site area. Subsoil drain was proposed as one of solution for groundwater seepage occurred at the slope face by reducing groundwater table at Taman Botani Park Kuala Lumpur. The simulation technique used Modular Three- Dimensional Finite Difference Groundwater Flow (MODFLOW) software. In transient conditions, the results of simulation showed that heads increases surpass 1 to 2 m from the elevation level of the slope area that caused groundwater seepage on slope face. This study attempt to decrease the heads increase surpass by using different sub-soil drain size in simulation technique. The sub-soil drain capable to decline the heads ranges of 1 to 2 m

Peat Stabilization by Using Sugarcane Bagasse Ash (SCBA) as a Partial Cement Replacement Materials

Malaysia are covered approximately 2.6 million hectare of peat and facing serious geotechnical problems to develop infrastructure on peatland area. This study is to observe the basic geotechnical properties, strength and compressibility behavior of Pontian peat that stabilized by cement (OPC) and sugarcane bagasse ash (SCBA). The whole laboratory test standards and regulation that had been used in this study was adopted from American Society for Testing and Materials (ASTM) and British standards (BS). In order to understand an improvement of peat stabilization, unconfined compressive strength (UCS) and 1D-Oedometer consolidation test were conducted on untreated and stabilized peat. The results show that Pontian peat can be considered as hemic peat with average acidic. It was observed that the treated peat with 5% of SCBA (PCB5) has the highest UCS of 190 kPa and was discovered to be equivalent to PC specimen. There was a noteworthy decrease of void ratio, e for optimum PCB and PC mixtures as compared to untreated peat. The value of Cc and Cα was quite low at small effective stresses, however it improved after beyond preconsolidation pressure, σ’c. Compared to untreated Pontian peat which contributed the ratio of Cα/Cc about 0.056, stabilized peat for PC and PCB5 gave better ratio with 0.0316 and 0.0273 respectively. Results shows that the treated peat Cα/Cc ratios were drop dramatically from untreated peat which is representing the stabilized mixture can efficiently reduce the secondary compression

Modelling Technique for the Assessment of the Sub-Soil Drain for Groundwater Seepage Remediation

Groundwater simulation technique was carried out for examining the performance of sub-soil drain at problematic site area. Subsoil drain was proposed as one of solution for groundwater seepage occurred at the slope face by reducing groundwater table at Taman Botani Park Kuala Lumpur. The simulation technique used Modular Three-Dimensional Finite Difference Groundwater Flow (MODFLOW) software. In transient conditions, the results of simulation showed that heads increases surpass 1 to 2 m from the elevation level of the slope area that caused groundwater seepage on slope face. This study attempt to decrease the heads increase surpass by using different sub-soil drain size in simulation technique. The sub-soil drain capable to decline the heads ranges of 1 to 2 m

Using tourism as a mechanism to reduce poaching and hunting: a case study of the Tidong community, Sabah

"In Sabah, Malaysia, illegal hunting has increased in recent years putting considerable pressure on large mammal populations. The causes for this phenomenon lie in increasing rural poverty, ineffective policies to regulate hunting, as well as a ready market for many wildlife products in the Chinese medicine markets. This paper examines how Community-Based Ecotourism has some potential to be used as a tool to reducing poaching using the Tidong community in Sabah as a case study. The key finding is that successful conservation outcomes for Community-Based Ecotourism projects are only sustainable over the long run if projects are structured to ensure that the local community is able to continue effective management once sponsoring organizations hand over control and that revenue from tourism does not decline. If tourist revenue declines communities may be forced to revert to previous practices reversing any initial conservation gains.