UTM Consultation and Research team from FKA has been appointed to investigate the potential to re open Gunung Pulai Reserve Park to public. The first proposal was accepted, for re opening of the park. To increase the safety of the public, currently the Johor Government has approved new budget to Install the Early Warning System for mud flood protection . The team consists of Geologists, Surveyors, Geotechnical Engineers and Hydrologist.
Mount Pulai (Malay: Gunung Pulai) is a mountain in Johor, Malaysia which is located about 19 km from Johor Bahru city.It is also the name of another mountain located in Baling, Kedah which is 600 metres tall. It takes approximately four hours to reach the peak of the mountain from the base.It is the main site that carries radio and television towards Johor Bahru and surrounding areas.
Temuramah di BERNAMA 24 bersama tuan bri (Mentor Pelaburan Hartanah Muslim) berkenaan dengan hartanah di Johor. Di dalam temuramah 30 minit membincangkan potensi pelaburan hartanah terutama di Johor Baharu.
Soil acts as a sponge to take up and retain water. Movement of water into soil is called infiltration, and the downward movement of water within the soil is called percolation, permeability or hydraulic conductivity. Pore space in soil is the conduit that allows water to infiltrate and percolate.
In this topic we will learn and discuss on permeability, stresses in soil and flow net.
The last two to three decades have seen significant advances in the mechanics of unsaturated soils. It is now widely recognized that the fundamental principles in soil mechanics must cover both saturated and unsaturated soils. Nevertheless, there is still a great deal of uncertainties in the geotechnical community about how soil mechanics principles well-established for saturated soils can be extended to unsaturated soils. There is even wide skepticism about the necessity of such extension in engineering practice. This paper discusses some common pitfalls related to the fundamental principles that govern the volume change, shear strength and hydromechanical behaviour of unsaturated soils. It also attempts to address the issue of engineering relevance of unsaturated soil mechanics.
KEY QUESTIONS?
In particular, some basic questions are often raised on the fundamental principles that govern the hydromechanical behaviour of unsaturated soils and on the engineering relevance:
(1) Reconstituted soil versus compacted soil. What are the main differences in the hydromechanical behaviour of these soils? What are the implications of different pore size distributions (PSD), in constitutive modelling of unsaturated soils? Can a reconstituted soil become collapsible?
(2) Relationship between volume change, yield stress and shear strength. Can the constitutive equations for volume change, yield stress and shear strength be defined separately? Does the loading-collapse yield surface have to recover the apparent tensile strength surface? Do we need the suction-increase surface to capture possible plastic volume change when a soil is dried to a historically high suction? What are the implications of stress state variables in defining volume change and shear strength equations?
(3) Implications of using a Bishop effective stress. Can we use a Bishop-type effective stress in modelling unsaturated soil behaviour and what are the implications?
(4) Engineering relevance. What is the relevance of the unsaturated soil mechanics in engineering practice? Is a design based on the saturated soil mechanics always conservative? Considering the difficulty and uncertainty in measuring or monitoring in-situ suctions, the applicability of the unsaturated soil mechanics to engineering practice has also been questioned. These questions represent some of the most fundamental issues in unsaturated soil mechanics. There are currently no unified answers to these questions.
Di dalam meningkat kapasiti Surau Al Taqwa , Bandar Baru Kangkar Pulai dari 300 orang ke 1200 orang. Pihak pengurusan Surau Al Taqwa telah merancang draf awal pembangunan. In Sya Allah moga perjalanan pembangunan ini berjalan lancar.
The unsaturated zone is the part of the subsurface between the land surface and the groundwater table. The definition of an unsaturated zone is that the water content is below saturation (for the specific soil). Hence, ‘unsaturated’ means that the pore spaces between the soil grain particles or the pore space in cracks and fissures are partially filled with water, partially with air. The unsaturated zone can be from meters to hundred of meters deep.
If an unsaturated zone exists below the ground surface the water infiltrating through the top soil will flow vertically through the unsaturated zone before the water recharges the saturated zone. From the unsaturated zone, the water is lost by i) plant uptake (transpiration), ii) direct soil evaporation and iii) recharge. In the unsaturated zone, the driving force for the flow of water is the vertical gradient of the hydraulic head (consisting of gravity and capillary forces), and the soil characteristics (unsaturated hydraulic conductivity).
The vertical flow through an unsaturated soil is solved numerically using the Richards Equation. This equation is developed by combining the Darcy’s law with the law of conservation of mass and the result is a partial differential equation for one-dimensional vertical flow in unsaturated soil.
Sebagai orang yang di beri tanggungjawab menguruskan Surau Al Taqwa di Kangkar Pulai. Adalah tanggungjawab saya dan rakan jawatankuasa merancang pembangunan fizikal, rohani dan kebajikan.
Pada 10 Mac 2016, kami (AJK Surau) di Surau Al Taqwa telah berusaha membantu satu keluarga fakir miskin di mana terdiri daripada 11 ahli keluarga. Kedua – dua ibu bapa tidak bekerja dan ada antara anak anak yang tidak bersekolah. Yang menyedihkan adalah salah seorang bayi keluarga ini di sah tidak cukup zat untuk penumbuh besaran. Bekalan makanan dan air amat terhad. Sokongan fizikal dan moral amat di perlukan oleh keluarga ini.
Bagi yang ingin lebih ramai asnaf menerima bantuan di kangkar pulai boleh menghubungi Tuan Wagiman Ederis 012-7948076 atau layari bit.ly/altaqwa
English
As a person who was given the responsibility on managing the Surau Al Taqwa in Kangkar Pulai,
Johor . It is the responsibility of committee members and me, on the planning the
development of the physical , spiritual and welfare .
On March 10, 2016 , we ( AJK Prayer ) at Surau Al Taqwa was trying to help a poor family
which consists of 11 family members . Currently the parents do not have a permanent work and
some of the children are not in school . Moreover, the youngest family member that is a baby
baby of 6 months has been confirmed by the doctor required further intensive care on his diet . Food supplies and water are scarce.
Physical and moral support is needed by the family .
For those that have further information on the ASNAF in Kangkar Pulai may contact
Mr. Wagiman 012-7948076 or visit bit.ly/altaqwa
An example of lateral earth pressure overturning a retaining wall
Lateral earth pressure is the pressure that soil exerts in the horizontal direction. The lateral earth pressure is important because it affects the consolidation behavior and strength of the soil and because it is considered in the design of geotechnical engineering structures such as retaining walls, basements, tunnels, deep foundations and braced excavations.
The coefficient of lateral earth pressure, K, is defined as the ratio of the horizontal effective stress, σ’h, to the vertical effective stress, σ’v. The effective stress is the intergranular stress calculated by subtracting the pore pressure from the total stress as described in soil mechanics. K for a particular soil deposit is a function of the soil properties and the stress history. The minimum stable value of K is called the active earth pressure coefficient, Ka; the active earth pressure is obtained, for example,when a retaining wall moves away from the soil. The maximum stable value of K is called the passive earth pressure coefficient, Kp; the passive earth pressure would develop, for example against a vertical plow that is pushing soil horizontally. For a level ground deposit with zero lateral strain in the soil, the “at-rest” coefficient of lateral earth pressure, K0 is obtained.
There are many theories for predicting lateral earth pressure; some are empirically based, and some are analytically derived.
At rest lateral earth pressure, represented as K0, is the in situ lateral pressure. It can be measured directly by a dilatometer test (DMT) or a borehole pressuremeter test (PMT). As these are rather expensive tests, empirical relations have been created in order to predict at rest pressure with less involved soil testing, and relate to the angle of shearing resistance. Two of the more commonly used are presented below.
The active state occurs when a retained soil mass is allowed to relax or deform laterally and outward (away from the soil mass) to the point of mobilizing its available full shear resistance (or engaged its shear strength) in trying to resist lateral deformation. That is, the soil is at the point of incipient failure by shearing due to unloading in the lateral direction. It is the minimum theoretical lateral pressure that a given soil mass will exert on a retaining that will move or rotate away from the soil until the soil active state is reached (not necessarily the actual in-service lateral pressure on walls that do not move when subjected to soil lateral pressures higher than the active pressure). The passive state occurs when a soil mass is externally forced laterally and inward (towards the soil mass) to the point of mobilizing its available full shear resistance in trying to resist further lateral deformation. That is, the soil mass is at the point of incipient failure by shearing due to loading in the lateral direction. It is the maximum lateral resistance that a given soil mass can offer to a retaining wall that is being pushed towards the soil mass. That is, the soil is at the point of incipient failure by shearing, but this time due to loading in the lateral direction. Thus active pressure and passive resistance define the minimum lateral pressure and the maximum lateral resistance possible from a given mass of soil.
Rankine theory
Rankine’s theory, developed in 1857,[4] is a stress field solution that predicts active and passive earth pressure. It assumes that the soil is cohesionless, the wall is frictionless, the soil-wall interface is vertical, the failure surface on which the soil moves is planar, and the resultant force is angled parallel to the backfill surface. The equations for active and passive lateral earth pressure coefficients are given below. Note that φ’ is the angle of shearing resistance of the soil and the backfill is inclined at angle β to the horizontal
For the case where β is 0, the above equations simplify to
Coulomb theory
Coulomb (1776)[5] first studied the problem of lateral earth pressures on retaining structures. He used limit equilibrium theory, which considers the failing soil block as a free bodyin order to determine the limiting horizontal earth pressure. The limiting horizontal pressures at failure in extension or compression are used to determine the Ka and Kprespectively. Since the problem is indeterminate,[6] a number of potential failure surfaces must be analysed to identify the critical failure surface (i.e. the surface that produces the maximum or minimum thrust on the wall). Mayniel (1908)[7] later extended Coulomb’s equations to account for wall friction, symbolized by δ. Müller-Breslau (1906)[8] further generalized Mayniel’s equations for a non-horizontal backfill and a non-vertical soil-wall interface (represented by angle θ from the vertical).
Instead of evaluating the above equations or using commercial software applications for this, books of tables for the most common cases can be used. Generally instead of Ka, the horizontal part Kah is tabulated. It is the same as Ka times cos(δ+θ).
The actual earth pressure force Ea is the sum of a part Eag due to the weight of the earth, a part Eap due to extra loads such as traffic, minus a part Eac due to any cohesion present.
Eag is the integral of the pressure over the height of the wall, which equates to Ka times the specific gravity of the earth, times one half the wall height squared.
In the case of a uniform pressure loading on a terrace above a retaining wall, Eap equates to this pressure times Ka times the height of the wall. This applies if the terrace is horizontal or the wall vertical. Otherwise, Eap must be multiplied by cosθ cosβ / cos(θ − β).
Eac is generally assumed to be zero unless a value of cohesion can be maintained permanently.
Eag acts on the wall’s surface at one third of its height from the bottom and at an angle δ relative to a right angle at the wall. Eap acts at the same angle, but at one half the height.
Caquot and Kerisel
In 1948, Albert Caquot (1881–1976) and Jean Kerisel (1908–2005) developed an advanced theory that modified Muller-Breslau’s equations to account for a non-planar rupture surface. They used a logarithmic spiral to represent the rupture surface instead. This modification is extremely important for passive earth pressure where there is soil-wall friction. Mayniel and Muller-Breslau’s equations are unconservative in this situation and are dangerous to apply. For the active pressure coefficient, the logarithmic spiral rupture surface provides a negligible difference compared to Muller-Breslau. These equations are too complex to use, so tables or computers are used instead.
Equivalent fluid pressure
Terzaghi and Peck, in 1948, developed empirical charts for predicting lateral pressures. Only the soil’s classification and backfill slope angle are necessary to use the charts.
Bell’s relationship
For soils with cohesion, Bell developed an analytical solution that uses the square root of the pressure coefficient to predict the cohesion’s contribution to the overall resulting pressure. These equations represent the total lateral earth pressure. The first term represents the non-cohesive contribution and the second term the cohesive contribution. The first equation is for an active situation and the second for passive situations.
Alhamdulillah.. we had initiate our first unsaturated soil mechanics research collaboration between UTM and USM. Thanks for Dr. Ahmad Safuan and Dr. Hetty for initiating the idea & continuous efforts. We love to welcome Dr. Mastura and Dr. Haris for this collaboration. The area of research that we will work together on the Rainfall induce slope. We hope the research will be a smooth sailing. In Sya Allah…
is the effective stress friction angle.
