What is the proper vinyl sheet pile driving method for different soil types?

“Pitch and drive” method is the most practical way of pile driving in loose soils especially when using short piles. Also called “set and drive”, this method installs piles one by one. However, with only one interlock in control, sheet piles have high tendencies of rotating from the axis and leaning forward or backward. Panel driving is recommended for the dense deposit of sands and compact cohesive soils such as heavy clay or in presence of obstructions. In this method, a number of piles are interlocked together before driving. The panel of piles is supported by guide frames and driven gradually in sequence, sometimes in a staggered manner. The method can achieve installations of longer piles in more difficult ground conditions with better results in sheet pile alignment and verticality. In cases of difficult ground conditions such as hard strata and the presence of obstructions, driving assistance is employed along with a proper selection of driving method and equipment. Jetting and drilling help by loosening or eliminating obstructions by creating pressure right under the tip of the sheet pile being driven. Long and slender PVC sheet piles require steel mandrels as supports when driven in such conditions. Mandrel, which shape is similar to sheet pile profiles, increases the rigidity of Plastic Sheet Pile and supports the weight of the driving equipment such as a vibro-hammer.

What is the proper machine to drive piles in different conditions?

Impact driving is suitable for all soil types but appears to create the highest degree of stress to sheet piles. It is more appropriate to cohesive soils and soft soils such as silts and peats, loose medium to coarse sand, and gravels free of rock inclusions. Drop hammers such as the hydraulic hammer are the common types of impact-driving machinery. Driving using vibratory hammers is ideal for non-cohesive or granular soils such as soft soils and round-grained sand or gravel. It has also shown satisfactory performance in sandy, silty, or softer clay soils. It is less effective in angular-grained materials and soils with a firm consistency. With the introduction of vibration, however, the sub-soil can be further compacted, increasing penetration resistance and ultimately-refusal. If this is the case, driving aids like jetting and drilling might be necessary.

What are the pvc sheet pile selection criteria for soil condition of different hardness?

General rule of the thumb: “the harder the soil, the stronger and stiffer sheet pile section should be used”. Driveability of a pile section is a consequence of its cross-sectional properties (thickness, depth, and width), designed shape, length, grade, and the applied load. Hardness of soil strata characterized by SPT or CPT values is used to predict soil resistance which is essential in the calculation of driving force to be applied. Knowing the range of force from the selected driving machine, corresponding sheet pile sections can be picked according to their yield strength and elastic modulus.

How should I choose a sheet pile section for soils with, say, SPT Value, N=30? Can I still consider using vinyl or shift to steel?

Every sheet pile material has a design purpose, strengths, and areas of improvement. The availability of different materials denotes the need for a special material for a specific application. Plastic or synthetic sheet piles for example are known for being light and corrosion-resistant; Steel sheet piles are recognized for their extraordinary strength and versatility; and so on.

Important Guidelines and Best Practices In Excavation Shoring Safety

Jan 31, 2022
4 min read

إرشادات هامة وأفضل الممارسات في مجال سلامة تدعيم الحفريات

One major cause of accidents in the construction industry is when open trenches/excavations start to cave in. In a study by A. Suruda, G. Smith, and S.P. Barker, at least seventy (70) workers die each year due to trench cave-ins.

أحد الأسباب الرئيسية للحوادث في صناعة البناء هو انهيار الخنادق/الحفريات المفتوحة. في دراسة أجراها كل من أ. سورودا، وج. سميث، وس.ب. باركر، يموت ما لا يقل عن سبعين (70) عاملاً كل عام بسبب انهيارات الخنادق.

Accidents and fatalities due to trench cave-ins can be mitigated with the proper implementation of construction safety standards, and the use of trench/excavation protection systems.

يمكن الحد من الحوادث والوفيات الناجمة عن انهيارات الخنادق من خلال التطبيق السليم لمعايير السلامة الإنشائية، واستخدام أنظمة حماية الخنادق/الحفريات.

BEST PRACTICE IN EXCAVATION WORKS

أفضل الممارسات في أعمال الحفر

Working in open excavations puts the workers at risk. It should be noted, however, that risks such as excavation collapse and other accidents can be prevented by observing excavation safety standards and practices.

يُعرّض العمل في الحفريات المكشوفة العمال للخطر. ومع ذلك، تجدر الإشارة إلى أنه يمكن تجنب مخاطر مثل انهيار الحفريات والحوادث الأخرى من خلال الالتزام بمعايير وممارسات السلامة في الحفريات.

The following should be considered before carrying out excavation works at the site

ينبغي مراعاة ما يلي قبل البدء بأعمال الحفر في الموقع::

Warning Signs and Barricades

علامات تحذيرية وحواجز

Prior to the start of any excavation, warning signs and barricades should be placed along the perimeter of the excavation of the project site. This is done to enclose the working area for the project, and to let passing vehicles and pedestrians know that excavations works are being carried out at the area.

قبل بدء أي أعمال حفر، يجب وضع لافتات تحذيرية وحواجز على طول محيط منطقة الحفر في موقع المشروع. ويتم ذلك لتطويق منطقة العمل الخاصة بالمشروع، ولإعلام المركبات والمشاة المارين بأن أعمال الحفر جارية في المنطقة.

These signs and barricades should also have lighting and/or reflectorized components in order to be seen by vehicles and pedestrians at night.

ينبغي أن تحتوي هذه اللافتات والحواجز أيضاً على إضاءة و/أو مكونات عاكسة حتى تتمكن المركبات والمشاة من رؤيتها ليلاً.

Having a Certified Safety Officer on Site

وجود مسؤول سلامة معتمد في الموقع

Having a Certified Safety Officer on site during excavation works is very important. A Safety Officer is a professional who has undergone training on basic occupational safety and health and must be certified by the Occupational Safety and Health Administration (OSHA).

يُعدّ وجود مسؤول سلامة معتمد في الموقع أثناء أعمال الحفر أمرًا بالغ الأهمية. مسؤول السلامة هو شخص متخصص خضع لتدريب في مجال السلامة والصحة المهنية الأساسية، ويجب أن يكون حاصلاً على شهادة من إدارة السلامة والصحة المهنية (OSHA).

The Safety Officer must be well-versed on the safety standards that must be implemented at the construction site. He/she is responsible in ensuring the safety of everyone working at the site. This includes inspecting the project site and identifying hazards that may compromise the safety of the workers and other individuals.

يجب أن يكون مسؤول السلامة مُلِمًّا تمامًا بمعايير السلامة الواجب تطبيقها في موقع البناء. وهو مسؤول عن ضمان سلامة جميع العاملين في الموقع، ويشمل ذلك فحص موقع المشروع وتحديد المخاطر التي قد تُعرِّض سلامة العمال وغيرهم للخطر.

The Safety Officer must also ensure that protective equipment such as PPEs for the workers are worn, and the appropriate excavation protection system is correctly installed at the sides of the excavation prior to working.

يجب على مسؤول السلامة أيضاً التأكد من ارتداء العمال لمعدات الحماية الشخصية، وأن نظام الحماية المناسب للحفر مثبت بشكل صحيح على جانبي الحفر قبل بدء العمل.

Excavation Protection Systems

أنظمة حماية الحفريات

The use of excavation protection systems is imperative for excavations where sloping/benching of the excavation sides is not possible. This is also required when the underlying soil at the project site is predominantly loose or soft and may collapse easily.

يُعدّ استخدام أنظمة حماية الحفريات أمراً بالغ الأهمية في الحفريات التي لا يُمكن فيها إنشاء منحدرات أو مصاطب على جوانب الحفر. كما يُعدّ ذلك ضرورياً أيضاً عندما تكون التربة الأساسية في موقع المشروع رخوة أو لينة في الغالب، وقابلة للانهيار بسهولة.

combination of trench sheets and trench boxes as excavation protection

Excavation protection systems such as sheet piles and trench boxes must be properly designed by a registered/professional design engineer.

يجب تصميم أنظمة حماية الحفريات مثل الألواح الخشبية وصناديق الخنادق بشكل صحيح من قبل مهندس تصميم مسجل/محترف.

Loads such as lateral earth pressure, surcharge from traffic and equipment loads, as well as hydrostatic pressure from the retained soil must be considered by the engineer to determine the most adequate and cost-effective excavation protection system.

يجب على المهندس مراعاة الأحمال مثل ضغط التربة الجانبي، والحمل الزائد الناتج عن حركة المرور وأحمال المعدات، بالإضافة إلى الضغط الهيدروستاتيكي من التربة المحتجزة لتحديد نظام حماية الحفر الأكثر ملاءمة وفعالية من حيث التكلفة.

The installation of such temporary structures prevents the collapse or cave-in of the retained soil while the excavation is open and/or people are working inside the excavation.

يمنع تركيب هذه الهياكل المؤقتة انهيار التربة المحتجزة أو انهيارها أثناء فتح الحفر و/أو أثناء عمل الناس داخل الحفر.

Figure 1. Typical trench shield/box (Source: OSHA)

Safe Access and Egress Points

نقاط دخول وخروج آمنة

Ingress and egress points allow workers to access the excavation safely. It is required by OSHA 2226-10R that excavations should have ladders, steps, and ramps installed at the site for excavations having depths of 4.00 feet (1.22 meters) or deeper.

تتيح نقاط الدخول والخروج للعمال الوصول إلى موقع الحفر بأمان. وينص معيار OSHA 2226-10R على ضرورة تركيب سلالم ودرجات ومنحدرات في مواقع الحفر التي يبلغ عمقها 1.22 متر (4 أقدام) أو أكثر.

In line with trench shields/boxes, the ladders, steps and ramps should also be properly designed and installed at the site to prevent accidents while carrying out construction works in the excavation.

تماشياً مع دروع/صناديق الخنادق، يجب أيضاً تصميم السلالم والدرجات والمنحدرات وتركيبها بشكل صحيح في الموقع لمنع الحوادث أثناء تنفيذ أعمال البناء في الحفر.